[Bug]: error: call of overloaded 'ldexp(long int, int)' is ambiguous

[mtelka]

Describe the issue

The compilation of abseil-cpp 20240116.3 fails on OpenIndiana with this error:

In file included from /usr/include/gtest/gtest.h:71,
                 from /data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv_test.cc:25:
/data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv_test.cc: In member function 'virtual void {anonymous}::FromChars_NearRoundingCasesExplicit_Test::TestBody()':
/data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv_test.cc:183:38: error: call of overloaded 'ldexp(long int, int)' is ambiguous
  183 |   EXPECT_EQ(ToDouble("5.e125"), ldexp(6653062250012735, 365));
      |                                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/math.h:35,
                 from /usr/gcc/14/include/c++/14.2.0/bits/std_abs.h:40,
                 from /usr/gcc/14/include/c++/14.2.0/cstdlib:81,
                 from /usr/gcc/14/include/c++/14.2.0/ext/string_conversions.h:43,
                 from /usr/gcc/14/include/c++/14.2.0/bits/basic_string.h:4154,
                 from /usr/gcc/14/include/c++/14.2.0/string:54,
                 from /usr/gcc/14/include/c++/14.2.0/stdexcept:39,
                 from /usr/gcc/14/include/c++/14.2.0/system_error:43,
                 from /data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv.h:18,
                 from /data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv_test.cc:15:
/usr/include/iso/math_iso.h:211:28: note: candidate: 'long double std::ldexp(long double, int)'
  211 |         inline long double ldexp(long double __X, int __Y) {
      |                            ^~~~~
/usr/include/iso/math_iso.h:171:22: note: candidate: 'float std::ldexp(float, int)'
  171 |         inline float ldexp(float __X, int __Y) { return __ldexpf(__X, __Y); }
      |                      ^~~~~
/usr/include/iso/math_iso.h:71:15: note: candidate: 'double std::ldexp(double, int)'
   71 | extern double ldexp(double, int);
      |               ^~~~~
/data/builds/oi-userland/components/library/abseil-cpp/abseil-cpp-20240116.3/absl/strings/charconv_test.cc:184:39: error: call of overloaded 'ldexp(long int, int)' is ambiguous
  184 |   EXPECT_EQ(ToDouble("69.e267"), ldexp(4705683757438170, 841));
      |                                  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/iso/math_iso.h:211:28: note: candidate: 'long double std::ldexp(long double, int)'
  211 |         inline long double ldexp(long double __X, int __Y) {
      |                            ^~~~~
/usr/include/iso/math_iso.h:171:22: note: candidate: 'float std::ldexp(float, int)'
  171 |         inline float ldexp(float __X, int __Y) { return __ldexpf(__X, __Y); }
      |                      ^~~~~
/usr/include/iso/math_iso.h:71:15: note: candidate: 'double std::ldexp(double, int)'
   71 | extern double ldexp(double, int);
      |               ^~~~~

Steps to reproduce the problem

Compile abseil-cpp 20240116.3 with -DABSL_BUILD_TESTING=ON and -DABSL_USE_EXTERNAL_GOOGLETEST=ON on OpenIndiana.

What version of Abseil are you using?

20240116.3

What operating system and version are you using?

OpenIndiana (illumos distro)

What compiler and version are you using?

$ gcc --version
gcc (OpenIndiana 14.2.0-oi-1) 14.2.0
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$

What build system are you using?

cmake version 3.31.5

Additional context

No response

[mtelka]

I worked around the issue by adding .0 to the first parameter of all ldexp() calls in the absl/strings/charconv_test.cc file (44 occurences).

BTW, similar problem is with the pow() call in absl/strings/internal/cord_rep_btree_test.cc. I use this patch as a temporay solution:

--- abseil-cpp-20240116.3/absl/strings/internal/cord_rep_btree_test.cc.orig
+++ abseil-cpp-20240116.3/absl/strings/internal/cord_rep_btree_test.cc
@@ -740,7 +740,7 @@
     std::uniform_int_distribution<int> dist_height(0, 3);
     std::uniform_int_distribution<int> dist_leaf(0, max_cap - 1);
     const int height = dist_height(rnd);
-    return (height ? pow(max_cap, height) : 0) + dist_leaf(rnd);
+    return (height ? pow(static_cast<long double>(max_cap), height) : 0) + dist_leaf(rnd);
   };
 
   for (int i = 0; i < 10000; ++i) {