[libc++] tests with picolibc: add has-compolete-fenv feature

The FE_* macros checked for in cfenv.pass.cpp are not required to be
defined, if the relevant options are available. Picolibc happens not to
provide these on some platforms.
Added a test in features.py to skip fenv test automatically.

Author: domin144

libcxx/test/std/depr/depr.c.headers/fenv_h.compile.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // Floating point exceptions are required for the FE_... macros to be defined.
-// XFAIL: LIBCXX-PICOLIBC-FIXME
+// REQUIRES: has-compolete-fenv
 
 // <fenv.h>
 

libcxx/test/std/numerics/cfenv/cfenv.syn/cfenv.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // Floating point exceptions are required for the FE_... macros to be defined.
-// XFAIL: LIBCXX-PICOLIBC-FIXME
+// REQUIRES: has-compolete-fenv
 
 // <cfenv>
 

libcxx/utils/libcxx/test/features.py

@@ -224,6 +224,35 @@ def _getAndroidDeviceApi(cfg):
           """,
         ),
     ),
+    # Some platform do not provide complete floating point environment.
+    Feature(
+        name="has-compolete-fenv",
+        when=lambda cfg: sourceBuilds(
+            cfg,
+            """
+            #include <fenv.h>
+
+            #if !( \
+                defined FE_DIVBYZERO \
+                && defined FE_INEXACT \
+                && defined FE_INVALID \
+                && defined FE_INEXACT \
+                && defined FE_OVERFLOW \
+                && defined FE_UNDERFLOW \
+                && defined FE_ALL_EXCEPT \
+                && defined FE_DOWNWARD \
+                && defined FE_TONEAREST \
+                && defined FE_TOWARDZERO \
+                && defined FE_UPWARD \
+                && defined FE_DFL_ENV \
+                && defined FE_INEXACT)
+            #error Floating point environment not complete
+            #endif
+
+            int main(int, char**) { return 0; }
+          """,
+        ),
+    ),
     # Check for a Windows UCRT bug (fixed in UCRT/Windows 10.0.20348.0):
     # https://developercommunity.visualstudio.com/t/utf-8-locales-break-ctype-functions-for-wchar-type/1653678
     Feature(