regexp/syntax: correctly print `^` BOL and `$` EOL

Fixes #12980.

Change-Id: I936db2f57f7c4dc80bb8ec32715c4c6b7bf0d708
Reviewed-on: https://go-review.googlesource.com/16112
Reviewed-by: Russ Cox <rsc@golang.org>

diff --git a/src/regexp/syntax/regexp.go b/src/regexp/syntax/regexp.go
index cea7d9e04fec70ac66435c0aae94398b07a57ba2..75822cf981e3442868cc1b20e8287b19ea394abd 100644 (file)
--- a/src/regexp/syntax/regexp.go
+++ b/src/regexp/syntax/regexp.go
@@ -166,9 +166,9 @@ func writeRegexp(b *bytes.Buffer, re *Regexp) {
        case OpAnyChar:
                b.WriteString(`(?s:.)`)
        case OpBeginLine:
-               b.WriteRune('^')
+               b.WriteString(`(?m:^)`)
        case OpEndLine:
-               b.WriteRune('$')
+               b.WriteString(`(?m:$)`)
        case OpBeginText:
                b.WriteString(`\A`)
        case OpEndText:

diff --git a/src/regexp/syntax/simplify_test.go b/src/regexp/syntax/simplify_test.go
index 879eff5be7ee3d9aa25489fb10180a708b633125..5d0f1dea5e738b5d3525c9b3e3c2064c6ebccd39 100644 (file)
--- a/src/regexp/syntax/simplify_test.go
+++ b/src/regexp/syntax/simplify_test.go
@@ -19,8 +19,8 @@ var simplifyTests = []struct {
        {`(ab)+`, `(ab)+`},
        {`(ab)?`, `(ab)?`},
        {`.`, `(?s:.)`},
-       {`^`, `^`},
-       {`$`, `$`},
+       {`^`, `(?m:^)`},
+       {`$`, `(?m:$)`},
        {`[ac]`, `[ac]`},
        {`[^ac]`, `[^ac]`},