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 <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Cuong Manh Le <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: dr2chase

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
 }

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
 }

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},
 	}
 

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)
+	}
+}