gc: fix select line number

Fixes #1393.

R=ken2
CC=golang-dev
https://golang.org/cl/4811054

src/cmd/gc/go.y

@@ -685,6 +685,7 @@ select_stmt:
 	LBODY caseblock_list '}'
 	{
 		$$ = nod(OSELECT, N, N);
+		$$->lineno = typesw->lineno;
 		$$->list = $4;
 		typesw = typesw->left;
 	}

src/cmd/gc/select.c

@@ -108,6 +108,7 @@ walkselect(Node *sel)
 	// optimization: one-case select: single op.
 	if(i == 1) {
 		cas = sel->list->n;
+		setlineno(cas);
 		l = cas->ninit;
 		if(cas->left != N) {  // not default:
 			n = cas->left;
@@ -165,6 +166,7 @@ walkselect(Node *sel)
 	// this rewrite is used by both the general code and the next optimization.
 	for(l=sel->list; l; l=l->next) {
 		cas = l->n;
+		setlineno(cas);
 		n = cas->left;
 		if(n == N)
 			continue;
@@ -238,6 +240,7 @@ walkselect(Node *sel)
 		}
 		
 		n = cas->left;
+		setlineno(n);
 		r = nod(OIF, N, N);
 		r->ninit = cas->ninit;
 		switch(n->op) {
@@ -283,6 +286,7 @@ walkselect(Node *sel)
 	sel->ninit = nil;
 
 	// generate sel-struct
+	setlineno(sel);
 	var = nod(OXXX, N, N);
 	tempname(var, ptrto(types[TUINT8]));
 	r = nod(OAS, var, mkcall("newselect", var->type, nil, nodintconst(sel->xoffset)));
@@ -292,6 +296,7 @@ walkselect(Node *sel)
 	// register cases
 	for(l=sel->list; l; l=l->next) {
 		cas = l->n;
+		setlineno(cas);
 		n = cas->left;
 		r = nod(OIF, N, N);
 		r->nbody = cas->ninit;
@@ -338,6 +343,7 @@ walkselect(Node *sel)
 	}
 
 	// run the select
+	setlineno(sel);
 	init = list(init, mkcall("selectgo", T, nil, var));
 	sel->nbody = init;
 

test/fixedbugs/bug347.go

@@ -0,0 +1,49 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"runtime"
+	"strings"
+)
+
+var t *struct {
+	c chan int
+}
+
+var c chan int
+
+func f() {
+	select {
+	case <-t.c:  // THIS IS LINE 22
+		break
+	case <-c:
+		break
+	}
+}
+
+func main() {
+	defer func() {
+		recover()
+		for i := 0;; i++ {
+			pc, file, line, ok := runtime.Caller(i)
+			if !ok {
+				print("BUG: bug347: cannot find caller\n")
+				return
+			}
+			if !strings.Contains(file, "bug347.go") || runtime.FuncForPC(pc).Name() != "main.f" {
+				// walk past runtime frames
+				continue
+			}
+			if line != 22 {
+				print("BUG: bug347: panic at ", file, ":", line, " in ", runtime.FuncForPC(pc).Name(), "\n")
+			}
+			return
+		}
+	}()
+	f()
+}