go/types, types2: check integer constant literal overflow

Fixes #54280.

Change-Id: I44a31daaace50bc90c96cd36387bd1a009d6a287
Reviewed-on: https://go-review.googlesource.com/c/go/+/424055
Reviewed-by: Robert Findley <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Run-TryBot: Robert Griesemer <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: griesemer

src/cmd/compile/internal/types2/expr.go

@@ -109,7 +109,11 @@ func (check *Checker) overflow(x *operand) {
 	// Untyped integer values must not grow arbitrarily.
 	const prec = 512 // 512 is the constant precision
 	if x.val.Kind() == constant.Int && constant.BitLen(x.val) > prec {
-		check.errorf(opPos(x.expr), "constant %s overflow", opName(x.expr))
+		op := opName(x.expr)
+		if op != "" {
+			op += " "
+		}
+		check.errorf(opPos(x.expr), "constant %soverflow", op)
 		x.val = constant.MakeUnknown()
 	}
 }
@@ -1344,6 +1348,9 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 			check.errorf(e, "malformed constant: %s", e.Value)
 			goto Error
 		}
+		// Ensure that integer values don't overflow (issue #54280).
+		x.expr = e // make sure that check.overflow below has an error position
+		check.overflow(x)
 
 	case *syntax.FuncLit:
 		if sig, ok := check.typ(e.Type).(*Signature); ok {

src/cmd/compile/internal/types2/testdata/fixedbugs/issue54280.go

@@ -0,0 +1,7 @@
+// Copyright 2022 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 p
+
+const C = 912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912 // ERROR constant overflow

src/go/types/check_test.go

@@ -352,7 +352,7 @@ func TestManual(t *testing.T) {
 }
 
 func TestLongConstants(t *testing.T) {
-	format := "package longconst\n\nconst _ = %s\nconst _ = %s // ERROR excessively long constant"
+	format := "package longconst\n\nconst _ = %s /* ERROR constant overflow */ \nconst _ = %s // ERROR excessively long constant"
 	src := fmt.Sprintf(format, strings.Repeat("1", 9999), strings.Repeat("1", 10001))
 	testFiles(t, nil, []string{"longconst.go"}, [][]byte{[]byte(src)}, false, nil)
 }

src/go/types/expr.go

@@ -110,7 +110,11 @@ func (check *Checker) overflow(x *operand, opPos token.Pos) {
 	// Untyped integer values must not grow arbitrarily.
 	const prec = 512 // 512 is the constant precision
 	if x.val.Kind() == constant.Int && constant.BitLen(x.val) > prec {
-		check.errorf(atPos(opPos), _InvalidConstVal, "constant %s overflow", opName(x.expr))
+		op := opName(x.expr)
+		if op != "" {
+			op += " "
+		}
+		check.errorf(atPos(opPos), _InvalidConstVal, "constant %soverflow", op)
 		x.val = constant.MakeUnknown()
 	}
 }
@@ -1300,6 +1304,8 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 			check.errorf(e, _InvalidConstVal, "malformed constant: %s", e.Value)
 			goto Error
 		}
+		// Ensure that integer values don't overflow (issue #54280).
+		check.overflow(x, e.Pos())
 
 	case *ast.FuncLit:
 		if sig, ok := check.typ(e.Type).(*Signature); ok {

src/go/types/testdata/fixedbugs/issue54280.go

@@ -0,0 +1,7 @@
+// Copyright 2022 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 p
+
+const C = 912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912 // ERROR constant overflow

test/const7.go

@@ -24,12 +24,12 @@ import (
 // which declares an untyped constant of the given length.
 // testProg compiles this package and checks for the absence or
 // presence of a constant literal error.
-func testProg(dir, name string, length int, ok bool) {
+func testProg(dir, name string, length int, msg string) {
 	var buf bytes.Buffer
 
 	fmt.Fprintf(&buf,
-		"package %s; const _ = %s // %d digits",
-		name, strings.Repeat("9", length), length,
+		"package %s; const _ = 0b%s // %d bits",
+		name, strings.Repeat("1", length), length,
 	)
 
 	filename := filepath.Join(dir, fmt.Sprintf("%s.go", name))
@@ -41,7 +41,7 @@ func testProg(dir, name string, length int, ok bool) {
 	cmd.Dir = dir
 	output, err := cmd.CombinedOutput()
 
-	if ok {
+	if msg == "" {
 		// no error expected
 		if err != nil {
 			log.Fatalf("%s: compile failed unexpectedly: %v", name, err)
@@ -53,7 +53,7 @@ func testProg(dir, name string, length int, ok bool) {
 	if err == nil {
 		log.Fatalf("%s: compile succeeded unexpectedly", name)
 	}
-	if !bytes.Contains(output, []byte("excessively long constant")) {
+	if !bytes.Contains(output, []byte(msg)) {
 		log.Fatalf("%s: wrong compiler error message:\n%s\n", name, output)
 	}
 }
@@ -69,7 +69,10 @@ func main() {
 	}
 	defer os.RemoveAll(dir)
 
-	const limit = 10000 // compiler-internal constant length limit
-	testProg(dir, "x1", limit, true)
-	testProg(dir, "x2", limit+1, false)
+	const bitLimit = 512
+	const charLimit = 10000 // compiler-internal constant length limit
+	testProg(dir, "x1", bitLimit, "")
+	testProg(dir, "x2", bitLimit+1, "constant overflow")
+	testProg(dir, "x3", charLimit-2, "constant overflow") // -2 because literal contains 0b prefix
+	testProg(dir, "x4", charLimit-1, "excessively long constant")
 }

test/fixedbugs/issue54280.go

@@ -0,0 +1,11 @@
+// errorcheck
+
+// Copyright 2022 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.
+
+// Don't crash in export of oversized integer constant.
+
+package p
+
+const C = 912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912_345_678_901_234_567_890_123_456_789_012_345_678_901_234_567_890_912 // ERROR "constant overflow"