Fix running golangci-lint in different packages

The built-in typecheck cannot run on single files and will cause a
compilation error as soon as we attempt to lint a file that requires a
file from the same package. As a best-effort workaround now linting
the entire package a file has been changed in in the pre-commit hook.

golangci/golangci-lint#1574 (comment)
golangci/golangci-lint#2912

Author: carhartl

go.yaml

@@ -7,10 +7,15 @@ pre-commit:
     golangci-lint:
       tags: lint go
       glob: "*.go"
-      # `golangci-lint run` requires all files to be in the same package
-      # when passing it named files, thus in order to only lint staged files
-      # in the pre-commit hook linting them one by one...
-      run: for file in {staged_files}; do golangci-lint run $file; done
+      # Cannot easily run `golangci-lint run` on single files as imported types from the
+      # same package will appear as undefined and cause a typecheck compilation error.
+      # https://github.com/golangci/golangci-lint/issues/1574#issuecomment-804500358
+      # https://github.com/golangci/golangci-lint/issues/2912
+      #
+      # Thus linting the entire package of a staged files..
+      run: |
+        packages=$(echo {staged_files} | xargs dirname | uniq)
+        for package in $packages; do golangci-lint run "$package"; done
 pre-push:
   parallel: true
   gotest: