cmd/go: always log dynamic import errors

There is no easy way to understand what user intent was and whether
they wanted to use a dynamic import or not.

If we skip logging such errors, it breaks common use cases such as
https://golang.org/issue/12810.

It's a better approach to expose the underlying mechanism and
be more verbose with the error messages.

Fixes #12810.

Change-Id: I7e922c9e848382690d9d9b006d7046e6cf93223b
Reviewed-on: https://go-review.googlesource.com/15756
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

diff --git a/src/cmd/go/vcs.go b/src/cmd/go/vcs.go
index 28a7540dfe43c0b14f929e94051a74eb6b1ae399..a1100960bffe6fb0b76aff79732a019f43a99ed7 100644 (file)
--- a/src/cmd/go/vcs.go
+++ b/src/cmd/go/vcs.go
@@ -567,16 +567,8 @@ func repoRootForImportPath(importPath string, security securityMode) (*repoRoot,
                        lookup = lookup[:i]
                }
                rr, err = repoRootForImportDynamic(lookup, security)
-
-               // repoRootForImportDynamic returns error detail
-               // that is irrelevant if the user didn't intend to use a
-               // dynamic import in the first place.
-               // Squelch it.
                if err != nil {
-                       if buildV {
-                               log.Printf("import %q: %v", importPath, err)
-                       }
-                       err = fmt.Errorf("unrecognized import path %q", importPath)
+                       err = fmt.Errorf("unrecognized import path %q (%v)", importPath, err)
                }
        }
        if err != nil {