1 files changed, 64 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/noder/scopes.go b/src/cmd/compile/internal/noder/scopes.go
new file mode 100644
index 0000000..eb51847
--- /dev/null
+++ b/src/cmd/compile/internal/noder/scopes.go
@@ -0,0 +1,64 @@
+// Copyright 2021 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 noder
+
+import (
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+)
+
+// recordScopes populates fn.Parents and fn.Marks based on the scoping
+// information provided by types2.
+func (g *irgen) recordScopes(fn *ir.Func, sig *syntax.FuncType) {
+	scope, ok := g.info.Scopes[sig]
+	if !ok {
+		base.FatalfAt(fn.Pos(), "missing scope for %v", fn)
+	}
+
+	for i, n := 0, scope.NumChildren(); i < n; i++ {
+		g.walkScope(scope.Child(i))
+	}
+
+	g.marker.WriteTo(fn)
+}
+
+func (g *irgen) walkScope(scope *types2.Scope) bool {
+	// types2 doesn't provide a proper API for determining the
+	// lexical element a scope represents, so we have to resort to
+	// string matching. Conveniently though, this allows us to
+	// skip both function types and function literals, neither of
+	// which are interesting to us here.
+	if strings.HasPrefix(scope.String(), "function scope ") {
+		return false
+	}
+
+	g.marker.Push(g.pos(scope))
+
+	haveVars := false
+	for _, name := range scope.Names() {
+		if obj, ok := scope.Lookup(name).(*types2.Var); ok && obj.Name() != "_" {
+			haveVars = true
+			break
+		}
+	}
+
+	for i, n := 0, scope.NumChildren(); i < n; i++ {
+		if g.walkScope(scope.Child(i)) {
+			haveVars = true
+		}
+	}
+
+	if haveVars {
+		g.marker.Pop(g.end(scope))
+	} else {
+		g.marker.Unpush()
+	}
+
+	return haveVars
+}