cmd/go: 'go list -test' prints main package twice

[dmitshur]

--- FAIL: TestCallgraph (1.60s)
    main_test.go:85: internal error: go list gives conflicting information for package pkg [pkg.test]
    main_test.go:85: internal error: go list gives conflicting information for package pkg [pkg.test]
FAIL
FAIL	golang.org/x/tools/cmd/callgraph	1.622s

From https://build.golang.org/?repo=golang.org%2fx%2ftools, it looks like the failure started to happen roughly close to 24781a1, but that might not be the exact commit.

Unfortunately, I can't reproduce it locally yet. For now, I'll send a CL to get more debug info out of the builders where it reproduces easily.

/cc @jayconrod @matloob

[gopherbot]

Change https://golang.org/cl/195617 mentions this issue: go/packages: include more detail in internal error

[dmitshur]

CL 195617 produced some more debug information:

--- FAIL: TestCallgraph (0.61s)
    main_test.go:85: internal error: go list gives conflicting information for package pkg [pkg.test]:
        old = &packages.jsonPackage{ImportPath:"pkg [pkg.test]", Dir:"/workdir/gopath/src/golang.org/x/tools/cmd/callgraph/testdata/src/pkg", Name:"main", Export:"", GoFiles:[]string{"pkg.go", "pkg_test.go"}, CompiledGoFiles:[]string{"pkg.go", "pkg_test.go"}, CFiles:[]string(nil), CgoFiles:[]string(nil), CXXFiles:[]string(nil), MFiles:[]string(nil), HFiles:[]string(nil), FFiles:[]string(nil), SFiles:[]string(nil), SwigFiles:[]string(nil), SwigCXXFiles:[]string(nil), SysoFiles:[]string(nil), Imports:[]string(nil), ImportMap:map[string]string(nil), Deps:[]string{"internal/bytealg", "internal/cpu", "runtime", "runtime/internal/atomic", "runtime/internal/math", "runtime/internal/sys", "unsafe"}, TestGoFiles:[]string{"pkg_test.go"}, TestImports:[]string(nil), XTestGoFiles:[]string(nil), XTestImports:[]string(nil), ForTest:"pkg", DepOnly:true, Error:(*packages.jsonPackageError)(nil)}
        new = &packages.jsonPackage{ImportPath:"pkg [pkg.test]", Dir:"/workdir/gopath/src/golang.org/x/tools/cmd/callgraph/testdata/src/pkg", Name:"main", Export:"", GoFiles:[]string{"pkg.go", "pkg_test.go"}, CompiledGoFiles:[]string{"pkg.go", "pkg_test.go"}, CFiles:[]string(nil), CgoFiles:[]string(nil), CXXFiles:[]string(nil), MFiles:[]string(nil), HFiles:[]string(nil), FFiles:[]string(nil), SFiles:[]string(nil), SwigFiles:[]string(nil), SwigCXXFiles:[]string(nil), SysoFiles:[]string(nil), Imports:[]string(nil), ImportMap:map[string]string(nil), Deps:[]string{"internal/bytealg", "internal/cpu", "runtime", "runtime/internal/atomic", "runtime/internal/math", "runtime/internal/sys", "unsafe"}, TestGoFiles:[]string{"pkg_test.go"}, TestImports:[]string(nil), XTestGoFiles:[]string(nil), XTestImports:[]string(nil), ForTest:"pkg", DepOnly:false, Error:(*packages.jsonPackageError)(nil)}
    main_test.go:85: internal error: go list gives conflicting information for package pkg [pkg.test]:
        old = &packages.jsonPackage{ImportPath:"pkg [pkg.test]", Dir:"/workdir/gopath/src/golang.org/x/tools/cmd/callgraph/testdata/src/pkg", Name:"main", Export:"", GoFiles:[]string{"pkg.go", "pkg_test.go"}, CompiledGoFiles:[]string{"pkg.go", "pkg_test.go"}, CFiles:[]string(nil), CgoFiles:[]string(nil), CXXFiles:[]string(nil), MFiles:[]string(nil), HFiles:[]string(nil), FFiles:[]string(nil), SFiles:[]string(nil), SwigFiles:[]string(nil), SwigCXXFiles:[]string(nil), SysoFiles:[]string(nil), Imports:[]string(nil), ImportMap:map[string]string(nil), Deps:[]string{"internal/bytealg", "internal/cpu", "runtime", "runtime/internal/atomic", "runtime/internal/math", "runtime/internal/sys", "unsafe"}, TestGoFiles:[]string{"pkg_test.go"}, TestImports:[]string(nil), XTestGoFiles:[]string(nil), XTestImports:[]string(nil), ForTest:"pkg", DepOnly:true, Error:(*packages.jsonPackageError)(nil)}
        new = &packages.jsonPackage{ImportPath:"pkg [pkg.test]", Dir:"/workdir/gopath/src/golang.org/x/tools/cmd/callgraph/testdata/src/pkg", Name:"main", Export:"", GoFiles:[]string{"pkg.go", "pkg_test.go"}, CompiledGoFiles:[]string{"pkg.go", "pkg_test.go"}, CFiles:[]string(nil), CgoFiles:[]string(nil), CXXFiles:[]string(nil), MFiles:[]string(nil), HFiles:[]string(nil), FFiles:[]string(nil), SFiles:[]string(nil), SwigFiles:[]string(nil), SwigCXXFiles:[]string(nil), SysoFiles:[]string(nil), Imports:[]string(nil), ImportMap:map[string]string(nil), Deps:[]string{"internal/bytealg", "internal/cpu", "runtime", "runtime/internal/atomic", "runtime/internal/math", "runtime/internal/sys", "unsafe"}, TestGoFiles:[]string{"pkg_test.go"}, TestImports:[]string(nil), XTestGoFiles:[]string(nil), XTestImports:[]string(nil), ForTest:"pkg", DepOnly:false, Error:(*packages.jsonPackageError)(nil)}
FAIL

The diff:

 &packages.jsonPackage{
 	[...]
-	DepOnly:true,
+	DepOnly:false,
 	[...]
 }

[matloob]

I'm able to reproduce it locally on tip. It doesn't reproduce on earlier versions of go.

(To reproduce locally you'll have to set your PATH to include tip go because go/packages starts go list as a subprocess)

[dmitshur]

Unfortunately, I can't reproduce it locally yet.

I figured out why it was failing to reproduce for me. I made the mistake of doing this:

PATH="$HOME/gotip/bin:$PATH" go version && go test -v ./cmd/callgraph

Instead of something else that would do what I actually intended:

PATH="$HOME/gotip/bin:$PATH" go version && \
  PATH="$HOME/gotip/bin:$PATH" go test -v ./cmd/callgraph

🤦‍♂

Oh well, mystery solved. Thanks @matloob, your comment helped me figure it out.