[libcxx] Fix libcxx test, integral.pass.cpp

[saturn691]

Remove strtoll functions for testing i128/u128.

Under AArch64, long long is defined as i64. When running the test integral.pass.cpp, it calls tries to call strtoll, which returns an i64, not an i128, therefore only keeping the lower 64 bits.

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[llvmbot]

@llvm/pr-subscribers-libcxx

Author: William (saturn691)

Changes

Remove strtoll functions for testing i128/u128.

Under AArch64, long long is defined as i64. When running the test integral.pass.cpp, it calls tries to call strtoll, which returns an i64, not an i128, therefore only keeping the lower 64 bits.

---

Full diff: https://github.com/llvm/llvm-project/pull/135355.diff

1 Files Affected:

• (modified) libcxx/test/support/charconv_test_helpers.h (-19)

diff --git a/libcxx/test/support/charconv_test_helpers.h b/libcxx/test/support/charconv_test_helpers.h
index fcae09478457b..89927df02e56d 100644
--- a/libcxx/test/support/charconv_test_helpers.h
+++ b/libcxx/test/support/charconv_test_helpers.h
@@ -19,7 +19,6 @@
 #include <string.h>
 #include <stdlib.h>
 #include <type_traits>
-
 #include "test_macros.h"
 
 #if TEST_STD_VER < 11
@@ -163,15 +162,6 @@ struct to_chars_test_base
 #ifndef TEST_HAS_NO_INT128
     static TEST_CONSTEXPR_CXX23 __int128_t fromchars128_impl(char const* p, char const* ep, int base, true_type)
     {
-        if (!TEST_IS_CONSTANT_EVALUATED) {
-            char* last;
-            __int128_t r = strtoll(p, &last, base);
-            if(errno != ERANGE) {
-                assert(last == ep);
-                return r;
-            }
-        }
-
         // When the value doesn't fit in a long long use from_chars. This is
         // not ideal since it does a round-trip test instead if using an
         // external source.
@@ -185,15 +175,6 @@ struct to_chars_test_base
 
     static TEST_CONSTEXPR_CXX23 __uint128_t fromchars128_impl(char const* p, char const* ep, int base, false_type)
     {
-        if (!TEST_IS_CONSTANT_EVALUATED) {
-            char* last;
-            __uint128_t r = strtoull(p, &last, base);
-            if(errno != ERANGE) {
-                assert(last == ep);
-                return r;
-            }
-        }
-
         __uint128_t r;
         std::from_chars_result s = std::from_chars(p, ep, r, base);
         assert(s.ec == std::errc{});

[cpplearner]

When running the test integral.pass.cpp, it calls tries to call strtoll, which returns an i64, not an i128, therefore only keeping the lower 64 bits.

If the correct result would be larger than LLONG_MAX, strtoll should set errno to ERANGE, and fromchars128_impl would then proceed to use from_chars instead.

Could you please elaborate on the problem that you want to fix?

[saturn691]

This is not the case when tested with picolibc under AArch64.
I'm trying to fix the failed test case integral.pass.cpp which relies on the function fromchars128_impl. Specifically, when tested with std::numeric_limits<__int128_t>::lowest(), it fails.

[philnik777]

@saturn691 That sounds more like a picolibc bug than a libc++ one.

[saturn691]

@philnik777 I've double checked right now, errno = ERANGE = 34 under picolibc. It may be another issue

[saturn691]

Closing, as this is a bug in picolibc after all.