<xlocale>: boolalpha extraction should be case-sensitive #1541
Description
Reported by @b7f7 in ea1aaf7#commitcomment-45101146 . Also tracked by Microsoft-internal VSO-1259300 / AB#1259300 .
This is a regression in VS 2019 16.8 caused by GH-1168. I developed a complete test case:
C:\Temp>type meow.cpp
#include <cassert>
#include <ios>
#include <sstream>
using namespace std;
enum class Parse { Success, Failure };
struct TestCase {
const char* str;
ios_base::fmtflags flags;
Parse expected;
bool result;
};
// clang-format off
constexpr TestCase test_cases[] = {
{"0", ios_base::fmtflags{}, Parse::Success, false},
{"1", ios_base::fmtflags{}, Parse::Success, true },
{"2", ios_base::fmtflags{}, Parse::Failure, true }, // N4868 [facet.num.get.virtuals]/6
{"WOOF", ios_base::fmtflags{}, Parse::Failure, false}, // N4868 [facet.num.get.virtuals]/3.6
{"false", ios_base::boolalpha, Parse::Success, false},
{"true", ios_base::boolalpha, Parse::Success, true },
{"WOOF", ios_base::boolalpha, Parse::Failure, false}, // N4868 [facet.num.get.virtuals]/7
{"FALSE", ios_base::boolalpha, Parse::Failure, false}, // regressed by GH-1168
{"TRUE", ios_base::boolalpha, Parse::Failure, false}, // regressed by GH-1168
};
// clang-format on
int main() {
for (const auto& test : test_cases) {
bool val = !test.result;
istringstream iss(test.str);
iss.setf(test.flags);
iss >> val;
assert(iss.fail() == (test.expected == Parse::Failure));
assert(val == test.result);
}
}C:\Temp>cl /EHsc /nologo /W4 meow.cpp && meow
meow.cpp
Assertion failed: iss.fail() == (test.expected == Parse::Failure), file meow.cpp, line 35
The "FALSE" and "TRUE" cases are asserting because the Standard says that the extraction should fail, but the extraction is succeeding after GH-1168 modified _Getloctxt() to perform case-insensitive comparisons:
Line 3274 in 04369fc