diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,355 @@
+Mozilla Public License Version 2.0
+==================================
+
+### 1. Definitions
+
+**1.1. “Contributor”**
+    means each individual or legal entity that creates, contributes to
+    the creation of, or owns Covered Software.
+
+**1.2. “Contributor Version”**
+    means the combination of the Contributions of others (if any) used
+    by a Contributor and that particular Contributor's Contribution.
+
+**1.3. “Contribution”**
+    means Covered Software of a particular Contributor.
+
+**1.4. “Covered Software”**
+    means Source Code Form to which the initial Contributor has attached
+    the notice in Exhibit A, the Executable Form of such Source Code
+    Form, and Modifications of such Source Code Form, in each case
+    including portions thereof.
+
+**1.5. “Incompatible With Secondary Licenses”**
+    means
+
+* **(a)** that the initial Contributor has attached the notice described
+    in Exhibit B to the Covered Software; or
+* **(b)** that the Covered Software was made available under the terms of
+    version 1.1 or earlier of the License, but not also under the
+    terms of a Secondary License.
+
+**1.6. “Executable Form”**
+    means any form of the work other than Source Code Form.
+
+**1.7. “Larger Work”**
+    means a work that combines Covered Software with other material, in
+    a separate file or files, that is not Covered Software.
+
+**1.8. “License”**
+    means this document.
+
+**1.9. “Licensable”**
+    means having the right to grant, to the maximum extent possible,
+    whether at the time of the initial grant or subsequently, any and
+    all of the rights conveyed by this License.
+
+**1.10. “Modifications”**
+    means any of the following:
+
+* **(a)** any file in Source Code Form that results from an addition to,
+    deletion from, or modification of the contents of Covered
+    Software; or
+* **(b)** any new file in Source Code Form that contains any Covered
+    Software.
+
+**1.11. “Patent Claims” of a Contributor**
+    means any patent claim(s), including without limitation, method,
+    process, and apparatus claims, in any patent Licensable by such
+    Contributor that would be infringed, but for the grant of the
+    License, by the making, using, selling, offering for sale, having
+    made, import, or transfer of either its Contributions or its
+    Contributor Version.
+
+**1.12. “Secondary License”**
+    means either the GNU General Public License, Version 2.0, the GNU
+    Lesser General Public License, Version 2.1, the GNU Affero General
+    Public License, Version 3.0, or any later versions of those
+    licenses.
+
+**1.13. “Source Code Form”**
+    means the form of the work preferred for making modifications.
+
+**1.14. “You” (or “Your”)**
+    means an individual or a legal entity exercising rights under this
+    License. For legal entities, “You” includes any entity that
+    controls, is controlled by, or is under common control with You. For
+    purposes of this definition, “control” means **(a)** the power, direct
+    or indirect, to cause the direction or management of such entity,
+    whether by contract or otherwise, or **(b)** ownership of more than
+    fifty percent (50%) of the outstanding shares or beneficial
+    ownership of such entity.
+
+
+### 2. License Grants and Conditions
+
+#### 2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+* **(a)** under intellectual property rights (other than patent or trademark)
+    Licensable by such Contributor to use, reproduce, make available,
+    modify, display, perform, distribute, and otherwise exploit its
+    Contributions, either on an unmodified basis, with Modifications, or
+    as part of a Larger Work; and
+* **(b)** under Patent Claims of such Contributor to make, use, sell, offer
+    for sale, have made, import, and otherwise transfer either its
+    Contributions or its Contributor Version.
+
+#### 2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+#### 2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+* **(a)** for any code that a Contributor has removed from Covered Software;
+    or
+* **(b)** for infringements caused by: **(i)** Your and any other third party's
+    modifications of Covered Software, or **(ii)** the combination of its
+    Contributions with other software (except as part of its Contributor
+    Version); or
+* **(c)** under Patent Claims infringed by Covered Software in the absence of
+    its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+#### 2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+#### 2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+#### 2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+#### 2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+
+### 3. Responsibilities
+
+#### 3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+#### 3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+* **(a)** such Covered Software must also be made available in Source Code
+    Form, as described in Section 3.1, and You must inform recipients of
+    the Executable Form how they can obtain a copy of such Source Code
+    Form by reasonable means in a timely manner, at a charge no more
+    than the cost of distribution to the recipient; and
+
+* **(b)** You may distribute such Executable Form under the terms of this
+    License, or sublicense it under different terms, provided that the
+    license for the Executable Form does not attempt to limit or alter
+    the recipients' rights in the Source Code Form under this License.
+
+#### 3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+#### 3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+#### 3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+
+### 4. Inability to Comply Due to Statute or Regulation
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: **(a)** comply with
+the terms of this License to the maximum extent possible; and **(b)**
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+
+### 5. Termination
+
+**5.1.** The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated **(a)** provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and **(b)** on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+**5.2.** If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+**5.3.** In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+
+### 6. Disclaimer of Warranty
+
+> Covered Software is provided under this License on an “as is”
+> basis, without warranty of any kind, either expressed, implied, or
+> statutory, including, without limitation, warranties that the
+> Covered Software is free of defects, merchantable, fit for a
+> particular purpose or non-infringing. The entire risk as to the
+> quality and performance of the Covered Software is with You.
+> Should any Covered Software prove defective in any respect, You
+> (not any Contributor) assume the cost of any necessary servicing,
+> repair, or correction. This disclaimer of warranty constitutes an
+> essential part of this License. No use of any Covered Software is
+> authorized under this License except under this disclaimer.
+
+### 7. Limitation of Liability
+
+> Under no circumstances and under no legal theory, whether tort
+> (including negligence), contract, or otherwise, shall any
+> Contributor, or anyone who distributes Covered Software as
+> permitted above, be liable to You for any direct, indirect,
+> special, incidental, or consequential damages of any character
+> including, without limitation, damages for lost profits, loss of
+> goodwill, work stoppage, computer failure or malfunction, or any
+> and all other commercial damages or losses, even if such party
+> shall have been informed of the possibility of such damages. This
+> limitation of liability shall not apply to liability for death or
+> personal injury resulting from such party's negligence to the
+> extent applicable law prohibits such limitation. Some
+> jurisdictions do not allow the exclusion or limitation of
+> incidental or consequential damages, so this exclusion and
+> limitation may not apply to You.
+
+
+### 8. Litigation
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+
+### 9. Miscellaneous
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+
+### 10. Versions of the License
+
+#### 10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+#### 10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+#### 10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+#### 10.4. Distributing Source Code Form that is Incompatible With Secondary Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+## Exhibit A - Source Code Form License Notice
+
+    This Source Code Form is subject to the terms of the Mozilla Public
+    License, v. 2.0. If a copy of the MPL was not distributed with this
+    file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+## Exhibit B - “Incompatible With Secondary Licenses” Notice
+
+    This Source Code Form is "Incompatible With Secondary Licenses", as
+    defined by the Mozilla Public License, v. 2.0.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/changelog.md b/changelog.md
new file mode 100644
--- /dev/null
+++ b/changelog.md
@@ -0,0 +1,8 @@
+The [latest
+version](https://github.com/BlockScope/ghc-corroborate/blob/main/changelog.md)
+of this changelog.
+
+# Initial Release
+## v0.1
+
+* Same API spanning GHC 8.0 to 9.2.
diff --git a/defaults.dhall b/defaults.dhall
new file mode 100644
--- /dev/null
+++ b/defaults.dhall
@@ -0,0 +1,19 @@
+{ version = "0.1.0"
+, author = "Phil de Joux"
+, maintainer = "phil.dejoux@blockscope.com"
+, copyright = "© 2020-2022 Phil de Joux, © 2020-2022 Block Scope Limited"
+, git = "https://github.com/BlockScope/ghc-corroborate.git"
+, bug-reports = "https://github.com/blockscope/ghc-corroborate/issues"
+, license = "MPL-2.0"
+, license-file = "LICENSE.md"
+, tested-with =
+    "GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.4, GHC == 8.10.7, GHC == 9.0.1, GHC == 9.2.2"
+, ghc-options =
+  [ "-Wall"
+  , "-Wincomplete-uni-patterns"
+  , "-Wcompat"
+  , "-Widentities"
+  , "-Wredundant-constraints"
+  ]
+, dependencies = [ "base >=4.9.1.0 && <5" ]
+}
diff --git a/ghc-corroborate.cabal b/ghc-corroborate.cabal
new file mode 100644
--- /dev/null
+++ b/ghc-corroborate.cabal
@@ -0,0 +1,131 @@
+cabal-version: 2.0
+
+-- This file has been generated from package.dhall by hpack version 0.34.6.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: c06f71ab11c1f9db2542a51a56013fd94163228fda52e359ab6648d0720d529a
+
+name:           ghc-corroborate
+version:        0.1.0
+synopsis:       An flatter API for GHC typechecker plugins
+description:    The GHC API changes over time. This package re-exports most GHC
+                          imports needed by typechecker plugins from its GHC.Corroborate module
+                          with a stable API over multiple GHC versions.
+category:       Type System, GHC, Plugin
+stability:      experimental
+homepage:       https://github.com/blockscope/ghc-corroborate#readme
+bug-reports:    https://github.com/blockscope/ghc-corroborate/issues
+author:         Phil de Joux
+maintainer:     phil.dejoux@blockscope.com
+copyright:      © 2020-2022 Phil de Joux, © 2020-2022 Block Scope Limited
+license:        MPL-2.0
+license-file:   LICENSE.md
+tested-with:
+    GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.4, GHC == 8.10.7, GHC == 9.0.1, GHC == 9.2.2
+build-type:     Simple
+extra-source-files:
+    LICENSE.md
+    changelog.md
+    defaults.dhall
+    package.dhall
+
+source-repository head
+  type: git
+  location: https://github.com/blockscope/ghc-corroborate
+
+library
+  exposed-modules:
+      GhcApi.Constraint
+      GhcApi.Predicate
+      GhcApi.GhcPlugins
+      GHC.Corroborate.Constraint
+      GHC.Corroborate.Evidence
+      GHC.Corroborate.Compare
+      GHC.Corroborate.Shim
+      GHC.Corroborate.Wrap
+      GHC.Corroborate.Divulge
+      GHC.Corroborate
+  ghc-options: -Wall -Wincomplete-uni-patterns -Wcompat -Widentities -Wredundant-constraints
+  build-depends:
+      base >=4.9.1.0 && <5
+    , ghc-tcplugins-extra
+  if impl(ghc >= 9.2) && impl(ghc < 9.4)
+    hs-source-dirs:
+        src-ghc-tree
+        src-ghc-9.2
+    build-depends:
+        ghc >=9.2 && <9.4
+  if impl(ghc >= 9.0) && impl(ghc < 9.2)
+    hs-source-dirs:
+        src-ghc-tree
+        src-ghc-9.0
+    build-depends:
+        ghc >=9.0 && <9.2
+  if impl(ghc >= 8.10.0) && impl(ghc < 9.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.10
+    build-depends:
+        ghc >=8.10 && <8.12
+  if impl(ghc >= 8.8.0) && impl(ghc < 8.10.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.8
+    build-depends:
+        ghc >=8.8 && <8.10
+    mixins:
+        ghc hiding ()
+      , ghc (TcRnTypes as TcRnTypes)
+      , ghc (Type as Type)
+      , ghc (TcRnTypes as Constraint)
+      , ghc (Type as Predicate)
+  if impl(ghc >= 8.6.0) && impl(ghc < 8.8.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.6
+    build-depends:
+        ghc >=8.6 && <8.8
+    mixins:
+        ghc hiding ()
+      , ghc (TcRnTypes as TcRnTypes)
+      , ghc (Type as Type)
+      , ghc (TcRnTypes as Constraint)
+      , ghc (Type as Predicate)
+  if impl(ghc >= 8.4.0) && impl(ghc < 8.6.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.4
+    build-depends:
+        ghc >=8.4 && <8.6
+    mixins:
+        ghc hiding ()
+      , ghc (TcRnTypes as TcRnTypes)
+      , ghc (Type as Type)
+      , ghc (TcRnTypes as Constraint)
+      , ghc (Type as Predicate)
+  if impl(ghc >= 8.2.0) && impl(ghc < 8.4.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.2
+    build-depends:
+        ghc >=8.2 && <8.4
+    mixins:
+        ghc hiding ()
+      , ghc (TcRnTypes as TcRnTypes)
+      , ghc (Type as Type)
+      , ghc (TcRnTypes as Constraint)
+      , ghc (Type as Predicate)
+  if impl(ghc >= 8.0.0) && impl(ghc < 8.2.0)
+    hs-source-dirs:
+        src-ghc-flat
+        src-ghc-8.0
+    build-depends:
+        ghc >=8.0 && <8.2
+    mixins:
+        ghc hiding ()
+      , ghc (TcRnTypes as TcRnTypes)
+      , ghc (Type as Type)
+      , ghc (TcRnTypes as Constraint)
+      , ghc (Type as Predicate)
+  default-language: Haskell2010
diff --git a/package.dhall b/package.dhall
new file mode 100644
--- /dev/null
+++ b/package.dhall
@@ -0,0 +1,138 @@
+let defs = ./defaults.dhall
+
+in  let testopts = [ "-rtsopts", "-threaded", "-with-rtsopts=-N" ]
+
+    in    defs
+        ⫽ { name = "ghc-corroborate"
+          , synopsis = "An flatter API for GHC typechecker plugins"
+          , description =
+              ''
+              The GHC API changes over time. This package re-exports most GHC
+                        imports needed by typechecker plugins from its GHC.Corroborate module
+                        with a stable API over multiple GHC versions.''
+          , category = "Type System, GHC, Plugin"
+          , github = "blockscope/ghc-corroborate"
+          , stability = "experimental"
+          , extra-source-files =
+            [ "LICENSE.md", "changelog.md", "defaults.dhall", "package.dhall" ]
+          , library =
+            { dependencies = defs.dependencies # [ "ghc-tcplugins-extra" ]
+            , exposed-modules =
+              [ "GhcApi.Constraint"
+              , "GhcApi.Predicate"
+              , "GhcApi.GhcPlugins"
+              , "GHC.Corroborate.Constraint"
+              , "GHC.Corroborate.Evidence"
+              , "GHC.Corroborate.Compare"
+              , "GHC.Corroborate.Shim"
+              , "GHC.Corroborate.Wrap"
+              , "GHC.Corroborate.Divulge"
+              , "GHC.Corroborate"
+              ]
+            , other-modules = [] : List Text
+            , when =
+              [ { condition = "impl(ghc >= 9.2) && impl(ghc < 9.4)"
+                , source-dirs = [ "src-ghc-tree", "src-ghc-9.2" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=9.2 && <9.4"
+                    , mixin = [] : List Text
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 9.0) && impl(ghc < 9.2)"
+                , source-dirs = [ "src-ghc-tree", "src-ghc-9.0" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=9.0 && <9.2"
+                    , mixin = [] : List Text
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.10.0) && impl(ghc < 9.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.10" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.10 && <8.12"
+                    , mixin = [] : List Text
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.8.0) && impl(ghc < 8.10.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.8" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.8 && <8.10"
+                    , mixin =
+                      [ "hiding ()"
+                      , "(TcRnTypes as TcRnTypes)"
+                      , "(Type as Type)"
+                      , "(TcRnTypes as Constraint)"
+                      , "(Type as Predicate)"
+                      ]
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.6.0) && impl(ghc < 8.8.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.6" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.6 && <8.8"
+                    , mixin =
+                      [ "hiding ()"
+                      , "(TcRnTypes as TcRnTypes)"
+                      , "(Type as Type)"
+                      , "(TcRnTypes as Constraint)"
+                      , "(Type as Predicate)"
+                      ]
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.4.0) && impl(ghc < 8.6.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.4" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.4 && <8.6"
+                    , mixin =
+                      [ "hiding ()"
+                      , "(TcRnTypes as TcRnTypes)"
+                      , "(Type as Type)"
+                      , "(TcRnTypes as Constraint)"
+                      , "(Type as Predicate)"
+                      ]
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.2.0) && impl(ghc < 8.4.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.2" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.2 && <8.4"
+                    , mixin =
+                      [ "hiding ()"
+                      , "(TcRnTypes as TcRnTypes)"
+                      , "(Type as Type)"
+                      , "(TcRnTypes as Constraint)"
+                      , "(Type as Predicate)"
+                      ]
+                    }
+                  ]
+                }
+              , { condition = "impl(ghc >= 8.0.0) && impl(ghc < 8.2.0)"
+                , source-dirs = [ "src-ghc-flat", "src-ghc-8.0" ]
+                , dependencies =
+                  [ { name = "ghc"
+                    , version = ">=8.0 && <8.2"
+                    , mixin =
+                      [ "hiding ()"
+                      , "(TcRnTypes as TcRnTypes)"
+                      , "(Type as Type)"
+                      , "(TcRnTypes as Constraint)"
+                      , "(Type as Predicate)"
+                      ]
+                    }
+                  ]
+                }
+              ]
+            }
+          }
diff --git a/src-ghc-8.0/GHC/Corroborate.hs b/src-ghc-8.0/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.0/GHC/Corroborate.hs
@@ -0,0 +1,99 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+      -- ** GHC.Builtin.Types
+    , naturalTy, naturalTyCon
+      -- ** Class
+    , module Class
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import GhcPlugins
+    ( Plugin(..)
+    , defaultPlugin
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical
+    )
+import Predicate (PredTree(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..), WantedConstraints)
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar, tcSplitTyConApp_maybe)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(..)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import Class (Class)
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.0/GHC/Corroborate/Compare.hs b/src-ghc-8.0/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.0/GHC/Corroborate/Compare.hs
@@ -0,0 +1,13 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import qualified Type (cmpType, cmpTypes)
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon = compare
+
+cmpType :: Type -> Type -> Ordering
+cmpType = Type.cmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = Type.cmpTypes
diff --git a/src-ghc-8.0/GHC/Corroborate/Constraint.hs b/src-ghc-8.0/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.0/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,3 @@
+module GHC.Corroborate.Constraint (module TcPluginM) where
+
+import TcPluginM (newGiven)
diff --git a/src-ghc-8.0/GHC/Corroborate/Evidence.hs b/src-ghc-8.0/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.0/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvTerm] -> EvTerm
+evDFunApp' = EvDFunApp
+
+evCast' :: EvTerm -> TcCoercionR -> EvTerm
+evCast' = EvCast
+
+terms :: String -> Type -> Type -> [EvTerm]
+terms s t1 t2 = [evByFiat s t1 t2]
diff --git a/src-ghc-8.0/GhcApi/GhcPlugins.hs b/src-ghc-8.0/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.0/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (mkSubst)
diff --git a/src-ghc-8.10/GHC/Corroborate.hs b/src-ghc-8.10/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.10/GHC/Corroborate.hs
@@ -0,0 +1,106 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+      -- ** GHC.Builtin.Types
+    , naturalTy, naturalTyCon
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module HscTypes
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GhcPlugins
+    ( Plugin(..), PluginRecompile(..)
+    , defaultPlugin, purePlugin, impurePlugin, flagRecompile
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical, WantedConstraints
+    )
+import Predicate (Pred(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR, EvExpr, evCast, evDFunApp)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..))
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import HscTypes (HsParsedModule(..))
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.10/GHC/Corroborate/Compare.hs b/src-ghc-8.10/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.10/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-8.10/GHC/Corroborate/Constraint.hs b/src-ghc-8.10/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.10/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Constraint (newGiven) where
+
+import GhcApi.Constraint (CtEvidence)
+import Panic (panicDoc)
+import qualified TcPluginM (newGiven)
+import GHC.Corroborate
+
+-- | Create a new [G]iven constraint, with the supplied evidence. This must not
+-- be invoked from 'tcPluginInit' or 'tcPluginStop', or it will panic.
+newGiven :: CtLoc -> PredType -> EvTerm -> TcPluginM CtEvidence
+newGiven loc pty (EvExpr ev) = TcPluginM.newGiven loc pty ev
+newGiven _ _  ev = panicDoc "newGiven: not an EvExpr: " (ppr ev)
diff --git a/src-ghc-8.10/GHC/Corroborate/Evidence.hs b/src-ghc-8.10/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.10/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,18 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvExpr] -> EvTerm
+evDFunApp' = evDFunApp
+
+evCast' :: EvTerm -> TcCoercion -> EvTerm
+evCast' (EvExpr e)  = evCast e
+evCast' EvTypeable{} = error "Can't evCast EvTypeable{}"
+evCast' EvFun{} = error "Can't evCast EvFun{}"
+
+terms :: String -> Type -> Type -> [EvExpr]
+terms s t1 t2 =
+    case evByFiat s t1 t2 of
+        EvExpr e -> [e]
+        EvTypeable{} -> []
+        EvFun{} -> []
diff --git a/src-ghc-8.10/GhcApi/GhcPlugins.hs b/src-ghc-8.10/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.10/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (TcPlugin, mkSubst)
diff --git a/src-ghc-8.2/GHC/Corroborate.hs b/src-ghc-8.2/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.2/GHC/Corroborate.hs
@@ -0,0 +1,104 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+      -- ** GHC.Builtin.Types
+    , naturalTy, naturalTyCon
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module HscTypes
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import GhcPlugins
+    ( Plugin(..)
+    , defaultPlugin
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical
+    )
+import Predicate (PredTree(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..), WantedConstraints)
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import HscTypes (HsParsedModule(..))
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.2/GHC/Corroborate/Compare.hs b/src-ghc-8.2/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.2/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-8.2/GHC/Corroborate/Constraint.hs b/src-ghc-8.2/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.2/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,3 @@
+module GHC.Corroborate.Constraint (module TcPluginM) where
+
+import TcPluginM (newGiven)
diff --git a/src-ghc-8.2/GHC/Corroborate/Evidence.hs b/src-ghc-8.2/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.2/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvTerm] -> EvTerm
+evDFunApp' = EvDFunApp
+
+evCast' :: EvTerm -> TcCoercionR -> EvTerm
+evCast' = EvCast
+
+terms :: String -> Type -> Type -> [EvTerm]
+terms s t1 t2 = [evByFiat s t1 t2]
diff --git a/src-ghc-8.2/GhcApi/GhcPlugins.hs b/src-ghc-8.2/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.2/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (mkSubst)
diff --git a/src-ghc-8.4/GHC/Corroborate.hs b/src-ghc-8.4/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.4/GHC/Corroborate.hs
@@ -0,0 +1,105 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+    , naturalTy, naturalTyCon
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module HscTypes
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GhcPlugins
+    ( Plugin(..)
+    , defaultPlugin
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical
+    )
+import Predicate (PredTree(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..), WantedConstraints)
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import HscTypes (HsParsedModule(..))
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.4/GHC/Corroborate/Compare.hs b/src-ghc-8.4/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.4/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-8.4/GHC/Corroborate/Constraint.hs b/src-ghc-8.4/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.4/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,3 @@
+module GHC.Corroborate.Constraint (module TcPluginM) where
+
+import TcPluginM (newGiven)
diff --git a/src-ghc-8.4/GHC/Corroborate/Evidence.hs b/src-ghc-8.4/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.4/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvTerm] -> EvTerm
+evDFunApp' = EvDFunApp
+
+evCast' :: EvTerm -> TcCoercionR -> EvTerm
+evCast' = EvCast
+
+terms :: String -> Type -> Type -> [EvTerm]
+terms s t1 t2 = [evByFiat s t1 t2]
diff --git a/src-ghc-8.4/GhcApi/GhcPlugins.hs b/src-ghc-8.4/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.4/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (mkSubst)
diff --git a/src-ghc-8.6/GHC/Corroborate.hs b/src-ghc-8.6/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.6/GHC/Corroborate.hs
@@ -0,0 +1,105 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+    , naturalTy, naturalTyCon
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module HscTypes
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GhcPlugins
+    ( Plugin(..), PluginRecompile(..)
+    , defaultPlugin, purePlugin, impurePlugin, flagRecompile
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical
+    )
+import Predicate (PredTree(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR, EvExpr, evCast, evDFunApp)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..), WantedConstraints)
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import HscTypes (HsParsedModule(..))
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.6/GHC/Corroborate/Compare.hs b/src-ghc-8.6/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.6/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-8.6/GHC/Corroborate/Constraint.hs b/src-ghc-8.6/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.6/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Constraint (newGiven) where
+
+import GhcApi.Constraint (CtEvidence)
+import Panic (panicDoc)
+import qualified TcPluginM (newGiven)
+import GHC.Corroborate
+
+-- | Create a new [G]iven constraint, with the supplied evidence. This must not
+-- be invoked from 'tcPluginInit' or 'tcPluginStop', or it will panic.
+newGiven :: CtLoc -> PredType -> EvTerm -> TcPluginM CtEvidence
+newGiven loc pty (EvExpr ev) = TcPluginM.newGiven loc pty ev
+newGiven _ _  ev = panicDoc "newGiven: not an EvExpr: " (ppr ev)
diff --git a/src-ghc-8.6/GHC/Corroborate/Evidence.hs b/src-ghc-8.6/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.6/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,18 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvExpr] -> EvTerm
+evDFunApp' = evDFunApp
+
+evCast' :: EvTerm -> TcCoercion -> EvTerm
+evCast' (EvExpr e)  = evCast e
+evCast' EvTypeable{} = error "Can't evCast EvTypeable{}"
+evCast' EvFun{} = error "Can't evCast EvFun{}"
+
+terms :: String -> Type -> Type -> [EvExpr]
+terms s t1 t2 =
+    case evByFiat s t1 t2 of
+        EvExpr e -> [e]
+        EvTypeable{} -> []
+        EvFun{} -> []
diff --git a/src-ghc-8.6/GhcApi/GhcPlugins.hs b/src-ghc-8.6/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.6/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (mkSubst)
diff --git a/src-ghc-8.8/GHC/Corroborate.hs b/src-ghc-8.8/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.8/GHC/Corroborate.hs
@@ -0,0 +1,105 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GhcPlugins
+      module GhcPlugins
+      -- ** Constraint
+    , module Constraint
+      -- ** Predicate
+    , module Predicate
+      -- ** TcEvidence
+    , module TcEvidence
+      -- ** TcPluginM
+    , module TcPluginM
+      -- ** TcRnTypes
+    , module TcRnTypes
+      -- ** TcType
+    , module TcType
+      -- ** TyCoRep
+    , module TyCoRep
+      -- ** Unique
+    , module Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** TcTypeNats
+    , module TcTypeNats
+    , naturalTy, naturalTyCon
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module HscTypes
+      -- ** IOEnv
+    , module IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GhcPlugins
+    ( Plugin(..), PluginRecompile(..)
+    , defaultPlugin, purePlugin, impurePlugin, flagRecompile
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical
+    )
+import Predicate (PredTree(..), EqRel(..), classifyPredType)
+import TcEvidence (EvTerm(..), TcCoercion, TcCoercionR, EvExpr, evCast, evDFunApp)
+import TcPluginM
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified TcPluginM (tcLookupClass, tcLookupTyCon, lookupOrig)
+import TcRnTypes (TcPlugin(..), TcPluginResult(..), WantedConstraints)
+import TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import TyCoRep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import TysWiredIn (typeNatKind)
+import TcTypeNats (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import HscTypes (HsParsedModule(..))
+import IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPluginM.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPluginM.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPluginM.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-8.8/GHC/Corroborate/Compare.hs b/src-ghc-8.8/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.8/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-8.8/GHC/Corroborate/Constraint.hs b/src-ghc-8.8/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.8/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Constraint (newGiven) where
+
+import GhcApi.Constraint (CtEvidence)
+import Panic (panicDoc)
+import qualified TcPluginM (newGiven)
+import GHC.Corroborate
+
+-- | Create a new [G]iven constraint, with the supplied evidence. This must not
+-- be invoked from 'tcPluginInit' or 'tcPluginStop', or it will panic.
+newGiven :: CtLoc -> PredType -> EvTerm -> TcPluginM CtEvidence
+newGiven loc pty (EvExpr ev) = TcPluginM.newGiven loc pty ev
+newGiven _ _  ev = panicDoc "newGiven: not an EvExpr: " (ppr ev)
diff --git a/src-ghc-8.8/GHC/Corroborate/Evidence.hs b/src-ghc-8.8/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.8/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,18 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvExpr] -> EvTerm
+evDFunApp' = evDFunApp
+
+evCast' :: EvTerm -> TcCoercion -> EvTerm
+evCast' (EvExpr e)  = evCast e
+evCast' EvTypeable{} = error "Can't evCast EvTypeable{}"
+evCast' EvFun{} = error "Can't evCast EvFun{}"
+
+terms :: String -> Type -> Type -> [EvExpr]
+terms s t1 t2 =
+    case evByFiat s t1 t2 of
+        EvExpr e -> [e]
+        EvTypeable{} -> []
+        EvFun{} -> []
diff --git a/src-ghc-8.8/GhcApi/GhcPlugins.hs b/src-ghc-8.8/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-8.8/GhcApi/GhcPlugins.hs
@@ -0,0 +1,3 @@
+module GhcApi.GhcPlugins (module GhcPlugins) where
+
+import GhcPlugins hiding (TcPlugin, mkSubst)
diff --git a/src-ghc-9.0/GHC/Corroborate.hs b/src-ghc-9.0/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.0/GHC/Corroborate.hs
@@ -0,0 +1,106 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GHC.Plugins
+      module GHC.Plugins
+      -- ** GHC.Tc.Types.Constraint
+    , module GHC.Tc.Types.Constraint
+      -- ** GHC.Core.Predicate
+    , module GHC.Core.Predicate
+      -- ** GHC.Tc.Types.Evidence
+    , module GHC.Tc.Types.Evidence
+      -- ** GHC.Tc.Plugin
+    , module GHC.Tc.Plugin
+      -- ** GHC.Tc.Types
+    , module GHC.Tc.Types
+      -- ** GHC.Tc.Utils.TcType
+    , module GHC.Tc.Utils.TcType
+      -- ** GHC.Core.TyCo.Rep
+    , module GHC.Core.TyCo.Rep
+      -- ** GHC.Types.Unique
+    , module GHC.Types.Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** GHC.Builtin.Types
+    , naturalTy, naturalTyCon
+      -- ** GHC.Builtin.Types.Literals
+    , module GHC.Builtin.Types.Literals
+      -- ** GHC
+    , module GHC
+      -- ** HscTypes
+    , module GHC.Driver.Types
+      -- ** GHC.Data.IOEnv
+    , module GHC.Data.IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GHC.Plugins
+    ( Plugin(..), PluginRecompile(..)
+    , defaultPlugin, purePlugin, impurePlugin, flagRecompile
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..), FindResult(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, typeNatKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import GHC.Tc.Types.Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical, WantedConstraints
+    )
+import GHC.Core.Predicate (Pred(..), EqRel(..), classifyPredType)
+import GHC.Tc.Types.Evidence (EvTerm(..), TcCoercion, TcCoercionR, EvExpr, evCast, evDFunApp)
+import GHC.Tc.Plugin
+    ( TcPluginM, unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified GHC.Tc.Plugin as TcPlugin (tcLookupClass, tcLookupTyCon, lookupOrig)
+import GHC.Tc.Types (TcPlugin(..), TcPluginResult(..))
+import GHC.Tc.Utils.TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import GHC.Core.TyCo.Rep
+    ( UnivCoProvenance(PluginProv)
+    , Type(TyConApp, TyVarTy, AppTy, ForAllTy, FunTy)
+    )
+import GHC.Types.Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import GHC.Builtin.Types (typeNatKind)
+import GHC.Builtin.Types.Literals (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsModule(..))
+import GHC.Driver.Types (HsParsedModule(..))
+import GHC.Data.IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPlugin.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPlugin.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPlugin.lookupOrig
+
+naturalTy = typeNatKind
+naturalTyCon = typeNatKindCon
diff --git a/src-ghc-9.0/GHC/Corroborate/Compare.hs b/src-ghc-9.0/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.0/GHC/Corroborate/Compare.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon a b = getUnique a `nonDetCmpUnique` getUnique b
+
+cmpType :: Type -> Type -> Ordering
+cmpType = nonDetCmpType
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes = nonDetCmpTypes
diff --git a/src-ghc-9.0/GHC/Corroborate/Constraint.hs b/src-ghc-9.0/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.0/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Constraint (newGiven) where
+
+import GhcApi.Constraint (CtEvidence)
+import GHC.Utils.Panic (panicDoc)
+import qualified GHC.Tc.Plugin as TcPlugin (newGiven)
+import GHC.Corroborate
+
+-- | Create a new [G]iven constraint, with the supplied evidence. This must not
+-- be invoked from 'tcPluginInit' or 'tcPluginStop', or it will panic.
+newGiven :: CtLoc -> PredType -> EvTerm -> TcPluginM CtEvidence
+newGiven loc pty (EvExpr ev) = TcPlugin.newGiven loc pty ev
+newGiven _ _  ev = panicDoc "newGiven: not an EvExpr: " (ppr ev)
diff --git a/src-ghc-9.0/GHC/Corroborate/Evidence.hs b/src-ghc-9.0/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.0/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,18 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvExpr] -> EvTerm
+evDFunApp' = evDFunApp
+
+evCast' :: EvTerm -> TcCoercion -> EvTerm
+evCast' (EvExpr e)  = evCast e
+evCast' EvTypeable{} = error "Can't evCast EvTypeable{}"
+evCast' EvFun{} = error "Can't evCast EvFun{}"
+
+terms :: String -> Type -> Type -> [EvExpr]
+terms s t1 t2 =
+    case evByFiat s t1 t2 of
+        EvExpr e -> [e]
+        EvTypeable{} -> []
+        EvFun{} -> []
diff --git a/src-ghc-9.0/GhcApi/GhcPlugins.hs b/src-ghc-9.0/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.0/GhcApi/GhcPlugins.hs
@@ -0,0 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-dodgy-imports #-}
+
+module GhcApi.GhcPlugins (module GHC.Tc.Plugin) where
+
+import GHC.Tc.Plugin hiding (TcPlugin, mkSubst)
diff --git a/src-ghc-9.2/GHC/Corroborate.hs b/src-ghc-9.2/GHC/Corroborate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.2/GHC/Corroborate.hs
@@ -0,0 +1,101 @@
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+-- | The GHC API changes over time. This module re-exports most GHC imports
+-- needed by typechecker plugins and has a stable API over multiple GHC
+-- versions.
+module GHC.Corroborate
+    (
+      -- * Imports from
+      -- ** GHC.Plugins
+      module GHC.Plugins
+      -- ** GHC.Tc.Types.Constraint
+    , module GHC.Tc.Types.Constraint
+      -- ** GHC.Core.Predicate
+    , module GHC.Core.Predicate
+      -- ** GHC.Tc.Types.Evidence
+    , module GHC.Tc.Types.Evidence
+      -- ** GHC.Tc.Plugin
+    , module GHC.Tc.Plugin
+      -- ** GHC.Tc.Types
+    , module GHC.Tc.Types
+      -- ** GHC.Tc.Utils.TcType
+    , module GHC.Tc.Utils.TcType
+      -- ** GHC.Core.Type
+    , module GHC.Core.Type
+      -- ** GHC.Core.TyCo.Rep
+    , module GHC.Core.TyCo.Rep
+      -- ** GHC.Types.Unique
+    , module GHC.Types.Unique
+      -- ** GHC.TcPluginM.Extra
+    , module GHC.TcPluginM.Extra
+      -- ** GHC.Builtin.Types
+    , module GHC.Builtin.Types
+      -- ** GHC.Builtin.Types.Literals
+    , module GHC.Builtin.Types.Literals
+      -- ** GHC
+    , module GHC
+      -- ** GHC.Data.IOEnv
+    , module GHC.Data.IOEnv
+      -- * Alternatives
+    , tcLookupClass, tcLookupTyCon, lookupOrig
+    ) where
+
+import Prelude hiding ((<>))
+
+import GHC.Plugins
+    ( Plugin(..), PluginRecompile(..)
+    , defaultPlugin, purePlugin, impurePlugin, flagRecompile
+    , PredType, FastString(..), Role(..), TyCoVarSet, ModuleName, Module
+    , Kind, TyVar, Var, Id, DFunId, Coercion, TyCon(..), Outputable(..)
+    , (<>), (<+>), ($$), vcat
+    , isNumLitTy, isStrLitTy, isFamilyTyCon
+    , mkNumLitTy, mkStrLitTy
+    , mkTyConApp, mkTcTyVar, mkPrimEqPred, mkTyVarTy, isTcTyVar
+    , dataConName, dataConWrapId, promoteDataCon
+    , heqTyCon, heqDataCon
+    , consDataCon, nilDataCon
+    , typeKind, typeSymbolKind, typeSymbolKindCon, tyVarKind
+    , tyCoVarsOfType, tyCoVarsOfTypes, tyConDataCons
+    , mkModuleName, mkSysTvName
+    , getOccName, occName, occNameFS, mkTcOcc, occNameString
+    , text, fsLit, unpackFS, showSDocUnsafe
+    , tcSplitTyConApp_maybe, splitTyConApp_maybe
+    , nonDetCmpType, nonDetCmpTypes, thenCmp, getUnique
+    , mkUnivCo, elemVarSet, coreView
+    , boolTyCon, promotedTrueDataCon, promotedFalseDataCon
+    , getTyVar_maybe, splitTyConApp_maybe, splitFunTy_maybe
+    , unLoc, moduleNameString
+    )
+import GHC.Tc.Types.Constraint
+    ( Ct(..), CtLoc
+    , ctLoc, ctEvidence, ctPred, ctEvPred
+    , isGiven, isWanted, isGivenCt
+    , mkNonCanonical, WantedConstraints
+    )
+import GHC.Core.Predicate (Pred(..), EqRel(..), classifyPredType)
+import GHC.Tc.Types.Evidence (EvTerm(..), TcCoercion, TcCoercionR, EvExpr, evCast, evDFunApp)
+import GHC.Tc.Plugin
+    ( TcPluginM, FindResult(..)
+    , unsafeTcPluginTcM, tcPluginIO, tcPluginTrace, findImportedModule
+    , matchFam, newFlexiTyVar, zonkCt, newUnique, isTouchableTcPluginM
+    )
+import qualified GHC.Tc.Plugin as TcPlugin (tcLookupClass, tcLookupTyCon, lookupOrig)
+import GHC.Tc.Types (TcPlugin(..), TcPluginResult(..))
+import GHC.Tc.Utils.TcType (vanillaSkolemTv, tcGetTyVar_maybe, isMetaTyVar)
+import GHC.Core.TyCo.Rep (UnivCoProvenance(PluginProv), Type(..), cmpTyLit)
+import GHC.Core.Type (nonDetCmpTc)
+import GHC.Types.Unique (nonDetCmpUnique)
+import GHC.TcPluginM.Extra (evByFiat, tracePlugin, lookupModule, lookupName )
+import GHC.Builtin.Types (naturalTyCon, naturalTy)
+import GHC.Builtin.Types.Literals (typeNatAddTyCon, typeNatSubTyCon)
+import GHC (Class, HsParsedModule(..), HsModule(..))
+import GHC.Data.IOEnv (newMutVar, readMutVar, writeMutVar)
+
+{-# DEPRECATED tcLookupClass "Use 'GHC.Corroborate.Divulge.divulgeClass' instead" #-}
+tcLookupClass = TcPlugin.tcLookupClass
+
+{-# DEPRECATED tcLookupTyCon "Use 'GHC.Corroborate.Divulge.divulgeTyCon' instead" #-}
+tcLookupTyCon = TcPlugin.tcLookupTyCon
+
+{-# DEPRECATED lookupOrig "Use 'lookupName' instead" #-}
+lookupOrig = TcPlugin.lookupOrig
diff --git a/src-ghc-9.2/GHC/Corroborate/Compare.hs b/src-ghc-9.2/GHC/Corroborate/Compare.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.2/GHC/Corroborate/Compare.hs
@@ -0,0 +1,20 @@
+module GHC.Corroborate.Compare (cmpTyCon, cmpType, cmpTypes) where
+
+import GHC.Corroborate
+
+-- TODO: all this is deeply dodgy!  These comparison functions are
+-- non-deterministic, so we may end up getting different results on different
+-- runs.  Really we should replace them with deterministic versions.
+
+cmpTyCon :: TyCon -> TyCon -> Ordering
+cmpTyCon = nonDetCmpTc
+
+cmpType :: Type -> Type -> Ordering
+cmpType (LitTy x) (LitTy y) = cmpTyLit x y
+cmpType t1 t2 = nonDetCmpType t1 t2
+
+cmpTypes :: [Type] -> [Type] -> Ordering
+cmpTypes [] [] = EQ
+cmpTypes (t1:ts1) (t2:ts2) = cmpType t1 t2 `thenCmp` cmpTypes ts1 ts2
+cmpTypes [] _ = LT
+cmpTypes _ [] = GT
diff --git a/src-ghc-9.2/GHC/Corroborate/Constraint.hs b/src-ghc-9.2/GHC/Corroborate/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.2/GHC/Corroborate/Constraint.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Constraint (newGiven) where
+
+import GhcApi.Constraint (CtEvidence)
+import GHC.Utils.Panic (panicDoc)
+import qualified GHC.Tc.Plugin as TcPlugin (newGiven)
+import GHC.Corroborate
+
+-- | Create a new [G]iven constraint, with the supplied evidence. This must not
+-- be invoked from 'tcPluginInit' or 'tcPluginStop', or it will panic.
+newGiven :: CtLoc -> PredType -> EvTerm -> TcPluginM CtEvidence
+newGiven loc pty (EvExpr ev) = TcPlugin.newGiven loc pty ev
+newGiven _ _  ev = panicDoc "newGiven: not an EvExpr: " (ppr ev)
diff --git a/src-ghc-9.2/GHC/Corroborate/Evidence.hs b/src-ghc-9.2/GHC/Corroborate/Evidence.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.2/GHC/Corroborate/Evidence.hs
@@ -0,0 +1,18 @@
+module GHC.Corroborate.Evidence (evDFunApp', evCast', terms) where
+
+import GHC.Corroborate
+
+evDFunApp' :: DFunId -> [Type] -> [EvExpr] -> EvTerm
+evDFunApp' = evDFunApp
+
+evCast' :: EvTerm -> TcCoercion -> EvTerm
+evCast' (EvExpr e)  = evCast e
+evCast' EvTypeable{} = error "Can't evCast EvTypeable{}"
+evCast' EvFun{} = error "Can't evCast EvFun{}"
+
+terms :: String -> Type -> Type -> [EvExpr]
+terms s t1 t2 =
+    case evByFiat s t1 t2 of
+        EvExpr e -> [e]
+        EvTypeable{} -> []
+        EvFun{} -> []
diff --git a/src-ghc-9.2/GhcApi/GhcPlugins.hs b/src-ghc-9.2/GhcApi/GhcPlugins.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-9.2/GhcApi/GhcPlugins.hs
@@ -0,0 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-dodgy-imports #-}
+
+module GhcApi.GhcPlugins (module GHC.Tc.Plugin) where
+
+import GHC.Tc.Plugin hiding (TcPlugin, mkSubst)
diff --git a/src-ghc-flat/GHC/Corroborate/Divulge.hs b/src-ghc-flat/GHC/Corroborate/Divulge.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-flat/GHC/Corroborate/Divulge.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Divulge (divulgeTyCon, divulgeClass) where
+
+import GhcPlugins (TyCon, Module, mkTcOcc)
+import GHC.TcPluginM.Extra (lookupName )
+import TcPluginM (TcPluginM, tcLookupClass, tcLookupTyCon)
+import Class (Class)
+
+divulgeTyCon :: Module -> String -> TcPluginM TyCon
+divulgeTyCon md s = tcLookupTyCon =<< lookupName md (mkTcOcc s)
+
+divulgeClass :: Module -> String -> TcPluginM Class
+divulgeClass md s = tcLookupClass =<< lookupName md (mkTcOcc s)
diff --git a/src-ghc-flat/GHC/Corroborate/Shim.hs b/src-ghc-flat/GHC/Corroborate/Shim.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-flat/GHC/Corroborate/Shim.hs
@@ -0,0 +1,52 @@
+module GHC.Corroborate.Shim
+    ( tyVarsOfType
+    , tyVarsOfTypes
+    , promoteTyCon
+    , mkEqPred
+    , mkHEqPred
+    , mkFunnyEqEvidence
+    ) where
+
+import GHC.Corroborate
+import GHC.Corroborate.Evidence (evDFunApp', evCast', terms)
+
+tyVarsOfType :: Type -> TyCoVarSet
+tyVarsOfType = tyCoVarsOfType
+
+tyVarsOfTypes :: [Type] -> TyCoVarSet
+tyVarsOfTypes = tyCoVarsOfTypes
+
+promoteTyCon :: TyCon -> TyCon
+promoteTyCon = id
+
+mkEqPred :: Type -> Type -> Type
+mkEqPred = mkPrimEqPred
+
+mkHEqPred :: Type -> Type -> Type
+mkHEqPred t1 t2 = TyConApp heqTyCon [typeKind t1, typeKind t2, t1, t2]
+
+-- | Make up evidence for a fake equality constraint @t1 ~~ t2@ by
+-- coercing bogus evidence of type @t1 ~ t2@ (or its heterogeneous
+-- variant, in GHC 8.0).
+mkFunnyEqEvidence :: String -> Type -> Type -> Type -> EvTerm
+mkFunnyEqEvidence s t t1 t2 =
+    castFrom `evCast'` castTo
+    where
+        castFrom :: EvTerm
+        castFrom = evDFunApp' funId tys $ terms s t1 t2
+            where
+                funId :: Id
+                funId = dataConWrapId heqDataCon
+
+                tys :: [Kind]
+                tys = [typeKind t1, typeKind t2, t1, t2]
+
+        castTo :: TcCoercion
+        castTo =
+            mkUnivCo from Representational tySource t
+            where
+                from :: UnivCoProvenance
+                from = PluginProv s
+
+                tySource :: Type
+                tySource = mkHEqPred t1 t2
diff --git a/src-ghc-flat/GHC/Corroborate/Wrap.hs b/src-ghc-flat/GHC/Corroborate/Wrap.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-flat/GHC/Corroborate/Wrap.hs
@@ -0,0 +1,10 @@
+module GHC.Corroborate.Wrap (newUnique, newWantedCt, newGivenCt) where
+
+import GHC.Corroborate
+import GHC.TcPluginM.Extra (newGiven, newWanted)
+
+newWantedCt :: CtLoc -> PredType -> TcPluginM Ct
+newWantedCt loc = fmap mkNonCanonical . newWanted loc
+
+newGivenCt :: CtLoc -> PredType -> EvTerm -> TcPluginM Ct
+newGivenCt loc prd ev = mkNonCanonical <$> newGiven loc prd ev
diff --git a/src-ghc-flat/GhcApi/Constraint.hs b/src-ghc-flat/GhcApi/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-flat/GhcApi/Constraint.hs
@@ -0,0 +1,3 @@
+module GhcApi.Constraint (module Constraint) where
+
+import Constraint (Ct (..), CtEvidence (..), CtLoc, ctLoc, ctEvId, mkNonCanonical)
diff --git a/src-ghc-flat/GhcApi/Predicate.hs b/src-ghc-flat/GhcApi/Predicate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-flat/GhcApi/Predicate.hs
@@ -0,0 +1,3 @@
+module GhcApi.Predicate (mkPrimEqPred) where
+
+import Predicate (mkPrimEqPred)
diff --git a/src-ghc-tree/GHC/Corroborate/Divulge.hs b/src-ghc-tree/GHC/Corroborate/Divulge.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-tree/GHC/Corroborate/Divulge.hs
@@ -0,0 +1,12 @@
+module GHC.Corroborate.Divulge (divulgeTyCon, divulgeClass) where
+
+import GHC.Plugins (TyCon, Module, mkTcOcc)
+import GHC.TcPluginM.Extra (lookupName )
+import GHC.Tc.Plugin (TcPluginM, tcLookupClass, tcLookupTyCon)
+import GHC (Class)
+
+divulgeTyCon :: Module -> String -> TcPluginM TyCon
+divulgeTyCon md s = tcLookupTyCon =<< lookupName md (mkTcOcc s)
+
+divulgeClass :: Module -> String -> TcPluginM Class
+divulgeClass md s = tcLookupClass =<< lookupName md (mkTcOcc s)
diff --git a/src-ghc-tree/GHC/Corroborate/Shim.hs b/src-ghc-tree/GHC/Corroborate/Shim.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-tree/GHC/Corroborate/Shim.hs
@@ -0,0 +1,52 @@
+module GHC.Corroborate.Shim
+    ( tyVarsOfType
+    , tyVarsOfTypes
+    , promoteTyCon
+    , mkEqPred
+    , mkHEqPred
+    , mkFunnyEqEvidence
+    ) where
+
+import GHC.Corroborate
+import GHC.Corroborate.Evidence (evDFunApp', evCast', terms)
+
+tyVarsOfType :: Type -> TyCoVarSet
+tyVarsOfType = tyCoVarsOfType
+
+tyVarsOfTypes :: [Type] -> TyCoVarSet
+tyVarsOfTypes = tyCoVarsOfTypes
+
+promoteTyCon :: TyCon -> TyCon
+promoteTyCon = id
+
+mkEqPred :: Type -> Type -> Type
+mkEqPred = mkPrimEqPred
+
+mkHEqPred :: Type -> Type -> Type
+mkHEqPred t1 t2 = TyConApp heqTyCon [typeKind t1, typeKind t2, t1, t2]
+
+-- | Make up evidence for a fake equality constraint @t1 ~~ t2@ by
+-- coercing bogus evidence of type @t1 ~ t2@ (or its heterogeneous
+-- variant, in GHC 8.0).
+mkFunnyEqEvidence :: String -> Type -> Type -> Type -> EvTerm
+mkFunnyEqEvidence s t t1 t2 =
+    castFrom `evCast'` castTo
+    where
+        castFrom :: EvTerm
+        castFrom = evDFunApp' funId tys $ terms s t1 t2
+            where
+                funId :: Id
+                funId = dataConWrapId heqDataCon
+
+                tys :: [Kind]
+                tys = [typeKind t1, typeKind t2, t1, t2]
+
+        castTo :: TcCoercion
+        castTo =
+            mkUnivCo from Representational tySource t
+            where
+                from :: UnivCoProvenance
+                from = PluginProv s
+
+                tySource :: Type
+                tySource = mkHEqPred t1 t2
diff --git a/src-ghc-tree/GHC/Corroborate/Wrap.hs b/src-ghc-tree/GHC/Corroborate/Wrap.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-tree/GHC/Corroborate/Wrap.hs
@@ -0,0 +1,10 @@
+module GHC.Corroborate.Wrap (newUnique, newWantedCt, newGivenCt) where
+
+import GHC.Corroborate
+import GHC.TcPluginM.Extra (newGiven, newWanted)
+
+newWantedCt :: CtLoc -> PredType -> TcPluginM Ct
+newWantedCt loc = fmap mkNonCanonical . newWanted loc
+
+newGivenCt :: CtLoc -> PredType -> EvTerm -> TcPluginM Ct
+newGivenCt loc prd ev = mkNonCanonical <$> newGiven loc prd ev
diff --git a/src-ghc-tree/GhcApi/Constraint.hs b/src-ghc-tree/GhcApi/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-tree/GhcApi/Constraint.hs
@@ -0,0 +1,4 @@
+module GhcApi.Constraint (module GHC.Tc.Types.Constraint) where
+
+import GHC.Tc.Types.Constraint
+    (Ct (..), CtEvidence (..), CtLoc, ctLoc, ctEvId, mkNonCanonical)
diff --git a/src-ghc-tree/GhcApi/Predicate.hs b/src-ghc-tree/GhcApi/Predicate.hs
new file mode 100644
--- /dev/null
+++ b/src-ghc-tree/GhcApi/Predicate.hs
@@ -0,0 +1,3 @@
+module GhcApi.Predicate (mkPrimEqPred) where
+
+import GHC.Core.Predicate (mkPrimEqPred)
