cmd/go/internal/get: propagate server errors if no go-import tags are found

Updates #30748

Change-Id: Ic93c68c1c4b2728f383edfdb06371ecc79a6f7b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/189779
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

diff --git a/src/cmd/go/internal/get/vcs.go b/src/cmd/go/internal/get/vcs.go
index 6ae3cffd93cc4fbddbca5cbd8e440cbcd1ae0cdf..3ccfbb8837594e22cf86c7a8428184dbd984c9eb 100644 (file)
--- a/src/cmd/go/internal/get/vcs.go
+++ b/src/cmd/go/internal/get/vcs.go
@@ -661,7 +661,7 @@ func RepoRootForImportPath(importPath string, mod ModuleMode, security web.Secur
        if err == errUnknownSite {
                rr, err = repoRootForImportDynamic(importPath, mod, security)
                if err != nil {
-                       err = fmt.Errorf("unrecognized import path %q (%v)", importPath, err)
+                       err = fmt.Errorf("unrecognized import path %q: %v", importPath, err)
                }
        }
        if err != nil {
@@ -799,6 +799,13 @@ func repoRootForImportDynamic(importPath string, mod ModuleMode, security web.Se
        body := resp.Body
        defer body.Close()
        imports, err := parseMetaGoImports(body, mod)
+       if len(imports) == 0 {
+               if respErr := resp.Err(); respErr != nil {
+                       // If the server's status was not OK, prefer to report that instead of
+                       // an XML parse error.
+                       return nil, respErr
+               }
+       }
        if err != nil {
                return nil, fmt.Errorf("parsing %s: %v", importPath, err)
        }
@@ -909,6 +916,13 @@ func metaImportsForPrefix(importPrefix string, mod ModuleMode, security web.Secu
                body := resp.Body
                defer body.Close()
                imports, err := parseMetaGoImports(body, mod)
+               if len(imports) == 0 {
+                       if respErr := resp.Err(); respErr != nil {
+                               // If the server's status was not OK, prefer to report that instead of
+                               // an XML parse error.
+                               return setCache(fetchResult{url: url, err: respErr})
+                       }
+               }
                if err != nil {
                        return setCache(fetchResult{url: url, err: fmt.Errorf("parsing %s: %v", resp.URL, err)})
                }
@@ -962,7 +976,7 @@ func (m ImportMismatchError) Error() string {
 
 // matchGoImport returns the metaImport from imports matching importPath.
 // An error is returned if there are multiple matches.
-// errNoMatch is returned if none match.
+// An ImportMismatchError is returned if none match.
 func matchGoImport(imports []metaImport, importPath string) (metaImport, error) {
        match := -1