cmd/vet: copy changes from golang.org/x/tools to cmd/vet

This means bringing over the examples flag and sorting doc.go.

Subsequent changes will generalize the examples flag to a general
test naming flag, but let's start with the original code.

No more changes to golang.org/x/tools please. This should not have
happened (and letting it happen was partly my fault).

Change-Id: Ia879ea1d15d82372df14853f919263125dfb7b96
Reviewed-on: https://go-review.googlesource.com/14821
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 15 insertions, 6 deletions

diff --git a/src/cmd/vet/main.go b/src/cmd/vet/main.go
index 453cfe0ce0..fbba009d11 100644
--- a/src/cmd/vet/main.go
+++ b/src/cmd/vet/main.go
@@ -51,6 +51,14 @@ var experimental = map[string]bool{}
 // setTrueCount record how many flags are explicitly set to true.
 var setTrueCount int
 
+// dirsRun and filesRun indicate whether the vet is applied to directory or
+// file targets. The distinction affects which checks are run.
+var dirsRun, filesRun bool
+
+// includesNonTest indicates whether the vet is applied to non-test targets.
+// Certain checks are relevant only if they touch both test and non-test files.
+var includesNonTest bool
+
 // A triState is a boolean that knows whether it has been set to either true or false.
 // It is used to identify if a flag appears; the standard boolean flag cannot
 // distinguish missing from unset. It also satisfies flag.Value.
@@ -207,8 +215,6 @@ func main() {
 	if flag.NArg() == 0 {
 		Usage()
 	}
-	dirs := false
-	files := false
 	for _, name := range flag.Args() {
 		// Is it a directory?
 		fi, err := os.Stat(name)
@@ -217,15 +223,18 @@ func main() {
 			continue
 		}
 		if fi.IsDir() {
-			dirs = true
+			dirsRun = true
 		} else {
-			files = true
+			filesRun = true
+			if !strings.HasSuffix(name, "_test.go") {
+				includesNonTest = true
+			}
 		}
 	}
-	if dirs && files {
+	if dirsRun && filesRun {
 		Usage()
 	}
-	if dirs {
+	if dirsRun {
 		for _, name := range flag.Args() {
 			walkDir(name)
 		}