proc: use file:line at entry point in skipAutogeneratedWrappersOut (#2089)

The file:line information for the entrypoint is more acccurate than the
file:line information at a return point, which could be affected by a
compiler bug.

Fixes #2086

_fixtures/issue2086.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"runtime"
+)
+
+var i int
+
+type T struct{}
+
+func (t T) m() { stop() }
+
+func stop() {
+	runtime.Breakpoint()
+	i++
+}
+
+func main() { T{}.m() }

pkg/proc/proc_test.go

@@ -4839,5 +4839,21 @@ func TestRefreshCurThreadSelGAfterContinueOnceError(t *testing.T) {
 			t.Fatalf("wrong current location %s:%d (expected :9)", g.CurrentLoc.File, g.CurrentLoc.Line)
 		}
 	})
-
+}
+
+func TestStepoutOneliner(t *testing.T) {
+	// The heuristic detecting autogenerated wrappers when stepping out should
+	// not skip oneliner functions.
+	withTestProcess("issue2086", t, func(p *proc.Target, fixture protest.Fixture) {
+		assertNoError(p.Continue(), t, "Continue()")
+		assertLineNumber(p, t, 15, "after first continue")
+		assertNoError(p.StepOut(), t, "StepOut()")
+		if fn := p.BinInfo().PCToFunc(currentPC(p, t)); fn == nil || fn.Name != "main.T.m" {
+			t.Fatalf("wrong function after stepout %#v", fn)
+		}
+		assertNoError(p.StepOut(), t, "second StepOut()")
+		if fn := p.BinInfo().PCToFunc(currentPC(p, t)); fn == nil || fn.Name != "main.main" {
+			t.Fatalf("wrong fnuction after second stepout %#v", fn)
+		}
+	})
 }

pkg/proc/target_exec.go

@@ -888,7 +888,8 @@ func skipAutogeneratedWrappersOut(g *G, thread Thread, startTopframe, startRetfr
 		if frame.Current.Fn == nil {
 			return
 		}
-		if !isAutogenerated(frame.Current) {
+		file, line := frame.Current.Fn.cu.lineInfo.PCToLine(frame.Current.Fn.Entry, frame.Current.Fn.Entry)
+		if !isAutogenerated(Location{File: file, Line: line, Fn: frame.Current.Fn}) {
 			return &frames[i-1], &frames[i]
 		}
 	}