cmd/compile: use a non-fragile test for "does f contain closure c?"

The old test relied on naming conventions.  The new test
uses an explicit parent pointer chain initialized when the
closures are created (in the same place that the names
used in the older fragile test were assigned).

Fixes #70035.

Change-Id: Ie834103c7096e4505faaff3bed1fc6e918a21211
Reviewed-on: https://go-review.googlesource.com/c/go/+/622656
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

4 files changed, 37 insertions, 6 deletions

diff --git a/src/cmd/compile/internal/escape/solve.go b/src/cmd/compile/internal/escape/solve.go
index ef17bc48ef..32f5a771a3 100644
--- a/src/cmd/compile/internal/escape/solve.go
+++ b/src/cmd/compile/internal/escape/solve.go
@@ -318,9 +318,10 @@ func containsClosure(f, c *ir.Func) bool {
 		return false
 	}
 
-	// Closures within function Foo are named like "Foo.funcN..." or "Foo-rangeN".
-	// TODO(mdempsky): Better way to recognize this.
-	fn := f.Sym().Name
-	cn := c.Sym().Name
-	return len(cn) > len(fn) && cn[:len(fn)] == fn && (cn[len(fn)] == '.' || cn[len(fn)] == '-')
+	for p := c.ClosureParent; p != nil; p = p.ClosureParent {
+		if p == f {
+			return true
+		}
+	}
+	return false
 }
diff --git a/src/cmd/compile/internal/ir/func.go b/src/cmd/compile/internal/ir/func.go
index f9af358ef4..6354da3556 100644
--- a/src/cmd/compile/internal/ir/func.go
+++ b/src/cmd/compile/internal/ir/func.go
@@ -51,6 +51,8 @@ import (
 // the generated ODCLFUNC, but there is no
 // pointer from the Func back to the OMETHVALUE.
 type Func struct {
+	// if you add or remove a field, don't forget to update sizeof_test.go
+
 	miniNode
 	Body Nodes
 
@@ -76,6 +78,9 @@ type Func struct {
 	// Populated during walk.
 	Closures []*Func
 
+	// Parent of a closure
+	ClosureParent *Func
+
 	// Parents records the parent scope of each scope within a
 	// function. The root scope (0) has no parent, so the i'th
 	// scope's parent is stored at Parents[i-1].
@@ -516,6 +521,7 @@ func NewClosureFunc(fpos, cpos src.XPos, why Op, typ *types.Type, outerfn *Func,
 
 	fn.Nname.Defn = fn
 	pkg.Funcs = append(pkg.Funcs, fn)
+	fn.ClosureParent = outerfn
 
 	return fn
 }
diff --git a/src/cmd/compile/internal/ir/sizeof_test.go b/src/cmd/compile/internal/ir/sizeof_test.go
index 6331cceb4a..ea74296315 100644
--- a/src/cmd/compile/internal/ir/sizeof_test.go
+++ b/src/cmd/compile/internal/ir/sizeof_test.go
@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 180, 304},
+		{Func{}, 184, 312},
 		{Name{}, 96, 168},
 	}
 
diff --git a/src/cmd/compile/internal/rangefunc/rangefunc_test.go b/src/cmd/compile/internal/rangefunc/rangefunc_test.go
index 1d0bed05c8..acf0ef6e09 100644
--- a/src/cmd/compile/internal/rangefunc/rangefunc_test.go
+++ b/src/cmd/compile/internal/rangefunc/rangefunc_test.go
@@ -2119,3 +2119,27 @@ func TestTwoLevelReturnCheck(t *testing.T) {
 		t.Errorf("Expected y=3, got y=%d\n", y)
 	}
 }
+
+func Bug70035(s1, s2, s3 []string) string {
+	var c1 string
+	for v1 := range slices.Values(s1) {
+		var c2 string
+		for v2 := range slices.Values(s2) {
+			var c3 string
+			for v3 := range slices.Values(s3) {
+				c3 = c3 + v3
+			}
+			c2 = c2 + v2 + c3
+		}
+		c1 = c1 + v1 + c2
+	}
+	return c1
+}
+
+func Test70035(t *testing.T) {
+	got := Bug70035([]string{"1", "2", "3"}, []string{"a", "b", "c"}, []string{"A", "B", "C"})
+	want := "1aABCbABCcABC2aABCbABCcABC3aABCbABCcABC"
+	if got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+}