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<regex>: Permit escaping of closing brackets in POSIX regexes #5399

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Merged
merged 1 commit into from
Apr 22, 2025
Merged

<regex>: Permit escaping of closing brackets in POSIX regexes #5399

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1 change: 1 addition & 0 deletions stl/inc/regex
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Original file line number Diff line number Diff line change
Expand Up @@ -4348,6 +4348,7 @@ bool _Parser<_FwdIt, _Elem, _RxTraits>::_IsIdentityEscape(bool _In_character_cla
return true;
case _Meta_dot:
case _Meta_lsq:
case _Meta_rsq:
case _Meta_star:
case _Meta_caret:
case _Meta_dlr:
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13 changes: 8 additions & 5 deletions tests/std/tests/GH_005244_regex_escape_sequences/test.cpp
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Expand Up @@ -465,6 +465,13 @@ void test_gh_5244_atomescape_posix_common(syntax_option_type option) {
check_atomescape_identityescape("^", option);
check_atomescape_identityescape("$", option);

// Even though [ is special, ] is not,
// so the interpretation of the escape sequence \] is undefined
// according to the POSIX standard referenced in the C++ standard.
// But we treat \] as an identity escape in line with
// more recent versions of the POSIX standard.
check_atomescape_identityescape("]", option);

// Sections on "BRE Special Characters" and "ERE Special Characters":
// escaping ordinary characters is undefined -> reject
g_regexTester.should_throw(R"(\B)", error_escape, option);
Expand All @@ -478,9 +485,6 @@ void test_gh_5244_atomescape_posix_common(syntax_option_type option) {
g_regexTester.should_throw(R"(\W)", error_escape, option);
g_regexTester.should_throw(R"(\s)", error_escape, option);
g_regexTester.should_throw(R"(\S)", error_escape, option);

// while [ is special, ] is not
g_regexTester.should_throw(R"(\])", error_escape, option);
}

void test_gh_5244_atomescape_posix_not_awk(syntax_option_type option) {
Expand Down Expand Up @@ -519,8 +523,6 @@ void test_gh_5244_atomescape_basic_or_grep(syntax_option_type option) {
}

void test_gh_5244_atomescape_extended_egrep_awk(syntax_option_type option) {
test_gh_5244_atomescape_posix_common(option);

// check that the parser accepts escaped characters
// that are only special in extended regexes
check_atomescape_identityescape("+", option);
Expand Down Expand Up @@ -552,6 +554,7 @@ void test_gh_5244_atomescape_extended_or_egrep(syntax_option_type option) {

void test_gh_5244_atomescape_awk() {
test_gh_5244_atomescape_extended_egrep_awk(awk);
test_gh_5244_atomescape_posix_common(awk);

// awk-only escapes
check_atomescape_controlescape("\a", "a", awk);
Expand Down