sourcehut: fix gqlgen with -trimpath

pkgs/applications/version-management/sourcehut/fix-gqlgen-trimpath.nix

@@ -0,0 +1,32 @@
+{ unzip }:
+{
+  overrideModAttrs = (_: {
+    # No need to workaround -trimpath: it's not used in go-modules,
+    # but do download `go generate`'s dependencies nonetheless.
+    preBuild = ''
+      set -x
+      go generate ./loaders
+      go generate ./graph
+      set +x
+    '';
+  });
+
+  # Workaround:
+  #   go: git.sr.ht/~emersion/go-emailthreads@v0.0.0-20220412093310-4fd792e343ba: module lookup disabled by GOPROXY=off
+  #   tidy failed: go mod tidy failed: exit status 1
+  #   graph/generate.go:10: running "go": exit status 1
+  proxyVendor = true;
+
+  # Workaround -trimpath in the package derivation:
+  # https://github.com/99designs/gqlgen/issues/1537
+  # This is to give `go generate ./graph` access to gqlgen's *.gotpl files
+  # If it fails, the gqlgenVersion may have to be updated.
+  preBuild = let gqlgenVersion = "0.17.2"; in ''
+    set -x
+    ${unzip}/bin/unzip ''${GOPROXY#"file://"}/github.com/99designs/gqlgen/@v/v${gqlgenVersion}.zip
+    go generate ./loaders
+    go generate ./graph
+    rm -rf github.com
+    set +x
+  '';
+}