[gcc(refs/users/aoliva/heads/testme)] libstdc++: testsuite: complex proj requirements

[Alexandre Oliva]

https://gcc.gnu.org/g:4a6d546dbd1dd86396645c0c9f4fc2dd0a095986

commit 4a6d546dbd1dd86396645c0c9f4fc2dd0a095986
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Mon Jun 27 05:30:49 2022 -0300

    libstdc++: testsuite: complex proj requirements
    
    The template version of complex::proj returns its argument without
    testing for infinities, and that's all we have when neither C99
    complex nor C99 math functions are available, and it seems too hard to
    do better without isinf and copysign.
    
    I suppose just calling them and expecting users will supply
    specializations as needed has been ruled out, and so has refraining
    from defining it when it can't be implemented correctly.
    
    It's pointless to run the proj.cc test under these circumstances, so
    arrange for it to be skipped.  In an unusual way, after trying to
    introduce dg-require tests for ccomplex-or-cmath, and found their
    results to be misleading due to variations across -std=* versions.
    
    
    for  libstdc++-v3/ChangeLog
    
            * testsuite/26_numerics/complex/proj.cc: Skip test in the
            circumstances in which the implementation of proj is known to
            be broken.

Diff:
---
 libstdc++-v3/testsuite/26_numerics/complex/proj.cc | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/libstdc++-v3/testsuite/26_numerics/complex/proj.cc b/libstdc++-v3/testsuite/26_numerics/complex/proj.cc
index a053119197c..69f8153c06f 100644
--- a/libstdc++-v3/testsuite/26_numerics/complex/proj.cc
+++ b/libstdc++-v3/testsuite/26_numerics/complex/proj.cc
@@ -397,6 +397,19 @@ test03()
 int
 main()
 {
+  /* If neither of these macros is nonzero, proj calls a
+     specialization of the __complex_proj template, that just returns
+     its argument, without testing for infinities, rendering the whole
+     test pointless, and failing (as intended/noted in the
+     implementation) the cases that involve infinities.  Alas, the
+     normal ways to skip tests may not work: we don't have a test for
+     C99_COMPLEX, and these macros may vary depending on -std=*, but
+     macro tests wouldn't take them into account.  */
+#if ! (_GLIBCXX_USE_C99_COMPLEX || _GLIBCXX_USE_C99_MATH_TR1)
+  if (true)
+    return 0;
+#endif
+
   test01();
   test02();
   test03();