runtime: skip logical frames in runtime.Caller

This rewrites runtime.Caller in terms of stackExpander, which already
handles inlined frames and partially skipped frames. This also has the
effect of making runtime.Caller understand cgo frames if there is a cgo
symbolizer.

Updates #19348.

Change-Id: Icdf4df921aab5aa394d4d92e3becc4dd169c9a6e
Reviewed-on: https://go-review.googlesource.com/40270
Run-TryBot: David Lazar <lazard@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

1 files changed, 77 insertions, 0 deletions

diff --git a/test/inline_caller.go b/test/inline_caller.go
new file mode 100644
index 0000000000..79039a6bb5
--- /dev/null
+++ b/test/inline_caller.go
@@ -0,0 +1,77 @@
+// run -gcflags -l=4
+
+// Copyright 2017 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 (
+	"fmt"
+	"runtime"
+)
+
+type frame struct {
+	pc   uintptr
+	file string
+	line int
+	ok   bool
+}
+
+var (
+	skip        int
+	globalFrame frame
+)
+
+func f() {
+	g() // line 27
+}
+
+func g() {
+	h() // line 31
+}
+
+func h() {
+	x := &globalFrame
+	x.pc, x.file, x.line, x.ok = runtime.Caller(skip) // line 36
+}
+
+//go:noinline
+func testCaller(skp int) frame {
+	skip = skp
+	f() // line 42
+	frame := globalFrame
+	if !frame.ok {
+		panic(fmt.Sprintf("skip=%d runtime.Caller failed", skp))
+	}
+	return frame
+}
+
+type wantFrame struct {
+	funcName string
+	line     int
+}
+
+// -1 means don't care
+var expected = []wantFrame{
+	0: {"main.testCaller", 36},
+	1: {"main.testCaller", 31},
+	2: {"main.testCaller", 27},
+	3: {"main.testCaller", 42},
+	4: {"main.main", 68},
+	5: {"runtime.main", -1},
+	6: {"runtime.goexit", -1},
+}
+
+func main() {
+	for i := 0; i <= 6; i++ {
+		frame := testCaller(i) // line 68
+		fn := runtime.FuncForPC(frame.pc)
+		if expected[i].line >= 0 && frame.line != expected[i].line {
+			panic(fmt.Sprintf("skip=%d expected line %d, got line %d", i, expected[i].line, frame.line))
+		}
+		if fn.Name() != expected[i].funcName {
+			panic(fmt.Sprintf("skip=%d expected function %s, got %s", i, expected[i].funcName, fn.Name()))
+		}
+	}
+}