[PATCH] builtins: Guard builtins.cc against HUGE_VAL and NAN definitions

[Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>]

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trunk bootstrap recently broke on Solaris like this:

/vol/gcc/src/hg/master/local/gcc/builtins.cc:2104:8: error: pasting "CFN_BUILT_IN_" and "(" does not give a valid preprocessing token
 2104 |   case CFN_BUILT_IN_##MATHFN:   \
      |        ^~~~~~~~~~~~~
/vol/gcc/src/hg/master/local/gcc/builtins.cc:2112:3: note: in expansion of macro 'CASE_MATHFN'
 2112 |   CASE_MATHFN(MATHFN)    \
      |   ^~~~~~~~~~~
/vol/gcc/src/hg/master/local/gcc/builtins.cc:1967:5: note: in expansion of macro 'CASE_MATHFN_FLOATN'
 1967 |     CASE_MATHFN_FLOATN (HUGE_VAL)  \

and similarly for NAN.

It turns out this happens because <math.h> is included at some point,
which (in <iso/math_c99.h>) defines

#define	HUGE_VAL	(__builtin_huge_val())
#define	NAN		(__builtin_nanf(""))

While this only happpens on Solaris right now, the same issue would be
present on other targets when <math.h> gets included somehow.

To avoid this, this patch #undef's both macros.

Bootstrapped without regressions on i386-pc-solaris2.11 and
sparc-sun-solaris2.11.

Ok for trunk?

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2022-11-01  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc:
	* builtins.cc (mathfn_built_in_2): #undef HUGE_VAL, NAN.


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# HG changeset patch
# Parent  3e5ba66da20edf52cdfe371ea2244c91d770f64a
builtins: Guard builtins.cc against HUGE_VAL and NAN definitions

diff --git a/gcc/builtins.cc b/gcc/builtins.cc
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -1931,6 +1931,11 @@ mathfn_built_in_2 (tree type, combined_f
   built_in_function fcodef64x = END_BUILTINS;
   built_in_function fcodef128x = END_BUILTINS;
 
+  /* If <math.h> has been included somehow, HUGE_VAL and NAN definitions
+     break the uses below.  */
+#undef HUGE_VAL
+#undef NAN
+
   switch (fn)
     {
 #define SEQ_OF_CASE_MATHFN			\