Update CI to run and export benchmarks across several GHC versions

Author: tbagrel1

.github/workflows/ci.yaml

@@ -37,9 +37,20 @@ jobs:
     - name: Build
       run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal build --allow-newer --disable-tests --disable-benchmarks"
     - name: Haddock
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal --allow-newer haddock"
+      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal haddock --allow-newer"
     - name: cabal-docspec
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run cabal-docspec
+      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal-docspec"
+    - name: Build benchmarks
+      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal build linear-base:bench:bench --allow-newer"
+    - name: Run benchmarks
+      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal bench --allow-newer 2>&1 | tee benchmark_ghc${{ matrix.ghc-version }}.txt"
+    - name: Upload benchmark results
+      uses: actions/upload-artifact@v3
+      with:
+        name: linear-base_benchmarks_ghc${{ matrix.ghc-version }}
+        path: |
+          benchmark_ghc${{ matrix.ghc-version }}.txt
+        retention-days: 365
 
   ormolu:
     name: check formatting with ormolu

cabal.project

@@ -1 +1,7 @@
 packages: *.cabal
+
+-- We need the `--alloc-newer` flag on cabal invocations because otherwise a build plan cannot be found.
+-- But as of 2024-09-11, the latest version of the `unix` 2.8.5.1 package has a conditional bound on `filepath` depending on the `os-string` flag (see https://hackage.haskell.org/package/unix-2.8.5.1/dependencies).
+-- With no extra parameter or setting, we get a dependency conflict on `filepath`, as other libs use a version of `filepath` incompatible with the one `unix` wants.
+-- Setting `filepath` to 1.4.2.2 fixes that.
+constraints: filepath ==1.4.2.2