From: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Date: Tue, 19 Jan 2021 15:57:45 +0000 (+0700)
Subject: [dev.regabi] cmd/compile: use '%q' for printing rune values less than 128
X-Git-Tag: go1.17beta1~1539^2~70
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=9423d50d53f132d7d00f5126144736bfe65627b6;p=gostls13.git

[dev.regabi] cmd/compile: use '%q' for printing rune values less than 128

Fixes #43762

Change-Id: I51734c9b4ee2366a5dae53b2d27b363f4d5fe6c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/284592
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index ee6a62625a..0ebfb84286 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -589,20 +589,20 @@ func exprFmt(n Node, s fmt.State, prec int) {
 		}
 
 		if n.Type() == types.UntypedRune {
-			switch x, ok := constant.Int64Val(n.Val()); {
+			switch x, ok := constant.Uint64Val(n.Val()); {
 			case !ok:
 				fallthrough
 			default:
 				fmt.Fprintf(s, "('\\x00' + %v)", n.Val())
 
-			case ' ' <= x && x < utf8.RuneSelf && x != '\\' && x != '\'':
-				fmt.Fprintf(s, "'%c'", int(x))
+			case x < utf8.RuneSelf:
+				fmt.Fprintf(s, "%q", x)
 
-			case 0 <= x && x < 1<<16:
-				fmt.Fprintf(s, "'\\u%04x'", uint(int(x)))
+			case x < 1<<16:
+				fmt.Fprintf(s, "'\\u%04x'", x)
 
-			case 0 <= x && x <= utf8.MaxRune:
-				fmt.Fprintf(s, "'\\U%08x'", uint64(x))
+			case x <= utf8.MaxRune:
+				fmt.Fprintf(s, "'\\U%08x'", x)
 			}
 		} else {
 			fmt.Fprint(s, types.FmtConst(n.Val(), s.Flag('#')))
diff --git a/test/fixedbugs/issue43762.go b/test/fixedbugs/issue43762.go
new file mode 100644
index 0000000000..4544b6e496
--- /dev/null
+++ b/test/fixedbugs/issue43762.go
@@ -0,0 +1,11 @@
+// errorcheck
+
+// 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 p
+
+var _ = true == '\\' // ERROR "invalid operation: true == '\\\\'"
+var _ = true == '\'' // ERROR "invalid operation: true == '\\''"
+var _ = true == '\n' // ERROR "invalid operation: true == '\\n'"