pkg/proc: handle double inlined calls (go-delve#2880)

It's possible that an inlined function call also contains an inlined
sunroutine. In this case we should also parse the children of
inlined calls to ensure we don't lose this information.

_fixtures/doubleinline.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"strconv"
+)
+
+type Rectangle struct{}
+
+func (r *Rectangle) Height() int {
+	h, _ := strconv.ParseInt("7", 10, 0)
+	return int(h)
+}
+
+func (r *Rectangle) Width() int {
+	return 6
+}
+
+func (r *Rectangle) Area() int { return r.Height() * r.Width() }
+
+func main() {
+	var r Rectangle
+	runtime.Breakpoint()
+	fmt.Println(r.Area())
+}

pkg/proc/bininfo.go

@@ -2262,6 +2262,10 @@ func (bi *BinaryInfo) loadDebugInfoMapsInlinedCalls(ctxt *loadDebugInfoMapsConte
 
 			fl := fileLine{callfile, int(callline)}
 			bi.inlinedCallLines[fl] = append(bi.inlinedCallLines[fl], lowpc)
+
+			if entry.Children {
+				bi.loadDebugInfoMapsInlinedCalls(ctxt, reader, cu)
+			}
 		}
 		reader.SkipChildren()
 	}

pkg/proc/proc_test.go

@@ -3979,6 +3979,9 @@ func TestInlineBreakpoint(t *testing.T) {
 	}
 	withTestProcessArgs("testinline", t, ".", []string{}, protest.EnableInlining|protest.EnableOptimization, func(p *proc.Target, fixture protest.Fixture) {
 		pcs, err := proc.FindFileLocation(p, fixture.Source, 17)
+		if err != nil {
+			t.Fatal(err)
+		}
 		t.Logf("%#v\n", pcs)
 		if len(pcs) != 1 {
 			t.Fatalf("unable to get PC for inlined function call: %v", pcs)
@@ -3995,6 +3998,27 @@ func TestInlineBreakpoint(t *testing.T) {
 	})
 }
 
+func TestDoubleInlineBreakpoint(t *testing.T) {
+	// We should be able to set a breakpoint on an inlined function that
+	// has been inlined within an inlined function.
+	if ver, _ := goversion.Parse(runtime.Version()); ver.Major >= 0 && !ver.AfterOrEqual(goversion.GoVersion{Major: 1, Minor: 10, Rev: -1}) {
+		// Versions of go before 1.10 do not have DWARF information for inlined calls
+		t.Skip("inlining not supported")
+	}
+	withTestProcessArgs("doubleinline", t, ".", []string{}, protest.EnableInlining|protest.EnableOptimization, func(p *proc.Target, fixture protest.Fixture) {
+		fns, err := p.BinInfo().FindFunction("main.(*Rectangle).Height")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(fns) != 1 {
+			t.Fatalf("expected one function for Height, got %d", len(fns))
+		}
+		if len(fns[0].InlinedCalls) != 1 {
+			t.Fatalf("expected one inlined call for Height, got %d", len(fns[0].InlinedCalls))
+		}
+	})
+}
+
 func TestIssue951(t *testing.T) {
 	if ver, _ := goversion.Parse(runtime.Version()); ver.Major >= 0 && !ver.AfterOrEqual(goversion.GoVersion{Major: 1, Minor: 9, Rev: -1}) {
 		t.Skip("scopes not implemented in <=go1.8")