From 611b182190e759879b3988077daf7d52eb831b5e Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Wed, 11 Sep 2013 13:25:30 -0400
Subject: [PATCH] go/build: reject directory with only cgo files if cgo not in
 use

The old test for "no Go files" was p.Name == "", meaning we never
saw a Go package statement. That test fails if there are cgo files
that we parsed (and recorded the package name) but then chose
not to use (because cgo is not available).

Test the actual file lists instead.

Fixes #6078.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/13661043
---
 src/cmd/go/test.bash                 | 13 +++++++++++++
 src/cmd/go/testdata/src/cgotest/m.go |  5 +++++
 src/pkg/go/build/build.go            |  4 +++-
 3 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 src/cmd/go/testdata/src/cgotest/m.go

diff --git a/src/cmd/go/test.bash b/src/cmd/go/test.bash
index a2ba1ca95a..c5effe757e 100755
--- a/src/cmd/go/test.bash
+++ b/src/cmd/go/test.bash
@@ -167,6 +167,19 @@ elif ! grep testdata/shadow/root1/src/foo testdata/err >/dev/null; then
 fi
 unset GOPATH
 
+TEST go install fails with no buildable files
+export GOPATH=$(pwd)/testdata
+export CGO_ENABLED=0
+if ./testgo install cgotest 2>testdata/err; then
+	echo "go install cgotest succeeded unexpectedly"
+elif ! grep 'no buildable Go source files' testdata/err >/dev/null; then
+	echo "go install cgotest did not report 'no buildable Go source files'"
+	cat testdata/err
+	ok=false
+fi
+unset CGO_ENABLED
+unset GOPATH
+
 # Test that without $GOBIN set, binaries get installed
 # into the GOPATH bin directory.
 TEST install into GOPATH
diff --git a/src/cmd/go/testdata/src/cgotest/m.go b/src/cmd/go/testdata/src/cgotest/m.go
new file mode 100644
index 0000000000..4d68307cf0
--- /dev/null
+++ b/src/cmd/go/testdata/src/cgotest/m.go
@@ -0,0 +1,5 @@
+package cgotest
+
+import "C"
+
+var _ C.int
diff --git a/src/pkg/go/build/build.go b/src/pkg/go/build/build.go
index f259525f5e..be48df9d38 100644
--- a/src/pkg/go/build/build.go
+++ b/src/pkg/go/build/build.go
@@ -747,6 +747,8 @@ Found:
 			allTags["cgo"] = true
 			if ctxt.CgoEnabled {
 				p.CgoFiles = append(p.CgoFiles, name)
+			} else {
+				p.IgnoredGoFiles = append(p.IgnoredGoFiles, name)
 			}
 		} else if isXTest {
 			p.XTestGoFiles = append(p.XTestGoFiles, name)
@@ -756,7 +758,7 @@ Found:
 			p.GoFiles = append(p.GoFiles, name)
 		}
 	}
-	if p.Name == "" {
+	if len(p.GoFiles)+len(p.CgoFiles)+len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
 		return p, &NoGoError{p.Dir}
 	}