go/importer: don't return packages that are not fully type-checked

Fixes #20837.

Change-Id: I266519c26c8849da267b77e11abe7734d8275112
Reviewed-on: https://go-review.googlesource.com/47074
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/go/internal/srcimporter/srcimporter.go b/src/go/internal/srcimporter/srcimporter.go
index f259493fc7f2a547f6cd88246acbdfdb0eb2530a..50cf361dbb01be39207701deeedf7c0e91413009 100644 (file)
--- a/src/go/internal/srcimporter/srcimporter.go
+++ b/src/go/internal/srcimporter/srcimporter.go
@@ -136,8 +136,11 @@ func (p *Importer) ImportFrom(path, srcDir string, mode types.ImportMode) (*type
        }
        pkg, err = conf.Check(bp.ImportPath, p.fset, files, nil)
        if err != nil {
-               // return (possibly nil or incomplete) package with error (see #16088)
-               return pkg, fmt.Errorf("type-checking package %q failed (%v)", bp.ImportPath, err)
+               // Type-checking stops after the first error (types.Config.Error is not set),
+               // so the returned package is very likely incomplete. Don't return it since
+               // we don't know its condition: It's very likely unsafe to use and it's also
+               // not added to p.packages which may cause further problems (issue #20837).
+               return nil, fmt.Errorf("type-checking package %q failed (%v)", bp.ImportPath, err)
        }
 
        p.packages[bp.ImportPath] = pkg