From: Russ Cox <rsc@golang.org>
Date: Wed, 11 Sep 2013 15:59:19 +0000 (-0400)
Subject: runtime: show runtime.panic frame in traceback
X-Git-Tag: go1.2rc2~261
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fa4984d535b23c0d2b14650a8842d63083893af3;p=gostls13.git

runtime: show runtime.panic frame in traceback

Otherwise, if panic starts running deferred functions,
the code that panicked appears to be calling those
functions directly, which is not the case and can be
confusing.

For example:

main.Two()
        /Users/rsc/x.go:12 +0x2a
runtime.panic(0x20dc0, 0x2100cc010)
        /Users/rsc/g/go/src/pkg/runtime/panic.c:248 +0x106
main.One()
        /Users/rsc/x.go:8 +0x55

This makes clear(er) that main.Two is being called during
a panic, not as a direct call from main.One.

Fixes #5832.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/13302051
---

diff --git a/src/pkg/runtime/symtab.c b/src/pkg/runtime/symtab.c
index 053e255079..bdf96a1b6e 100644
--- a/src/pkg/runtime/symtab.c
+++ b/src/pkg/runtime/symtab.c
@@ -317,10 +317,17 @@ runtime·showframe(Func *f, G *gp)
 	static int32 traceback = -1;
 	String name;
 
-	if(m->throwing && gp != nil && (gp == m->curg || gp == m->caughtsig))
+	if(m->throwing > 0 && gp != nil && (gp == m->curg || gp == m->caughtsig))
 		return 1;
 	if(traceback < 0)
 		traceback = runtime·gotraceback(nil);
 	name = runtime·gostringnocopy((uint8*)runtime·funcname(f));
+
+	// Special case: always show runtime.panic frame, so that we can
+	// see where a panic started in the middle of a stack trace.
+	// See golang.org/issue/5832.
+	if(name.len == 7+1+5 && hasprefix(name, "runtime.panic"))
+		return 1;
+
 	return traceback > 1 || f != nil && contains(name, ".") && !hasprefix(name, "runtime.");
 }