cmd/go: fix mod_install_pkg_version

mainPackagesOnly now includes non-main packages matched by literal
arguments in the returned slice, since their errors must be reported.

GoFilesPackages attaches the same error to its package if
opts.MainOnly is true. This changes the error output of 'go run'
slightly, but it seems like an imporovement.

For #42088

Change-Id: I8f2942470383af5d4c9763022bc94338f5314b07
Reviewed-on: https://go-review.googlesource.com/c/go/+/310829
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 26 insertions, 6 deletions

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 98a695ca24..79c3a71f07 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -480,6 +480,7 @@ type ImportPathError interface {
 
 var (
 	_ ImportPathError = (*importError)(nil)
+	_ ImportPathError = (*mainPackageError)(nil)
 	_ ImportPathError = (*modload.ImportMissingError)(nil)
 	_ ImportPathError = (*modload.ImportMissingSumError)(nil)
 	_ ImportPathError = (*modload.DirectImportFromImplicitDependencyError)(nil)
@@ -2545,7 +2546,8 @@ func CheckPackageErrors(pkgs []*Package) {
 // mainPackagesOnly filters out non-main packages matched only by arguments
 // containing "..." and returns the remaining main packages.
 //
-// mainPackagesOnly sets a package's error if it is named by a literal argument.
+// mainPackagesOnly sets a non-main package's Error field and returns it if it
+// is named by a literal argument.
 //
 // mainPackagesOnly prints warnings for non-literal arguments that only match
 // non-main packages.
@@ -2557,12 +2559,12 @@ func mainPackagesOnly(pkgs []*Package, patterns []string) []*Package {
 		}
 	}
 
-	mainPkgs := make([]*Package, 0, len(pkgs))
+	matchedPkgs := make([]*Package, 0, len(pkgs))
 	mainCount := make([]int, len(patterns))
 	nonMainCount := make([]int, len(patterns))
 	for _, pkg := range pkgs {
 		if pkg.Name == "main" {
-			mainPkgs = append(mainPkgs, pkg)
+			matchedPkgs = append(matchedPkgs, pkg)
 			for i := range patterns {
 				if matchers[i] != nil && matchers[i](pkg.ImportPath) {
 					mainCount[i]++
@@ -2570,8 +2572,11 @@ func mainPackagesOnly(pkgs []*Package, patterns []string) []*Package {
 			}
 		} else {
 			for i := range patterns {
-				if matchers[i] == nil && patterns[i] == pkg.ImportPath && pkg.Error == nil {
-					pkg.Error = &PackageError{Err: ImportErrorf(pkg.ImportPath, "package %s is not a main package", pkg.ImportPath)}
+				if matchers[i] == nil && patterns[i] == pkg.ImportPath {
+					if pkg.Error == nil {
+						pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
+					}
+					matchedPkgs = append(matchedPkgs, pkg)
 				} else if matchers[i] != nil && matchers[i](pkg.ImportPath) {
 					nonMainCount[i]++
 				}
@@ -2584,7 +2589,19 @@ func mainPackagesOnly(pkgs []*Package, patterns []string) []*Package {
 		}
 	}
 
-	return mainPkgs
+	return matchedPkgs
+}
+
+type mainPackageError struct {
+	importPath string
+}
+
+func (e *mainPackageError) Error() string {
+	return fmt.Sprintf("package %s is not a main package", e.importPath)
+}
+
+func (e *mainPackageError) ImportPath() string {
+	return e.importPath
 }
 
 func setToolFlags(pkgs ...*Package) {
@@ -2679,6 +2696,9 @@ func GoFilesPackage(ctx context.Context, opts PackageOpts, gofiles []string) *Pa
 		}
 	}
 
+	if opts.MainOnly && pkg.Name != "main" && pkg.Error == nil {
+		pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
+	}
 	setToolFlags(pkg)
 
 	return pkg