[Bug modula2/104065] [12 Regression] trunk 20220117 fails to build modula2

["doko at debian dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104065

Matthias Klose <doko at debian dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|FIXED                       |---
             Status|RESOLVED                    |NEW

--- Comment #4 from Matthias Klose <doko at debian dot org> ---
reopening. the build failure is still there.

the branch currently has:

--- a/gcc/hwint.h
+++ b/gcc/hwint.h
@@ -257,11 +257,14 @@ exact_log2 (unsigned HOST_WIDE_INT x)
   (HOST_WIDE_INT_1U << (HOST_BITS_PER_WIDE_INT - 1))
 #define HOST_WIDE_INT_MAX (~(HOST_WIDE_INT_MIN))

+#ifndef __cplusplus
 extern HOST_WIDE_INT abs_hwi (HOST_WIDE_INT);
 extern unsigned HOST_WIDE_INT absu_hwi (HOST_WIDE_INT);
-extern HOST_WIDE_INT gcd (HOST_WIDE_INT, HOST_WIDE_INT);
 extern HOST_WIDE_INT pos_mul_hwi (HOST_WIDE_INT, HOST_WIDE_INT);
 extern HOST_WIDE_INT mul_hwi (HOST_WIDE_INT, HOST_WIDE_INT);
+#endif  /* !cplusplus.  */
+
+extern HOST_WIDE_INT gcd (HOST_WIDE_INT, HOST_WIDE_INT);
 extern HOST_WIDE_INT least_common_multiple (HOST_WIDE_INT, HOST_WIDE_INT);

 /* Like ctz_hwi, except 0 when x == 0.  */
@@ -316,6 +319,7 @@ zext_hwi (unsigned HOST_WIDE_INT src, unsigned int prec)
     }
 }

+#ifdef __cplusplus
 /* Compute the absolute value of X.  */

 inline HOST_WIDE_INT
@@ -374,5 +378,6 @@ mul_hwi (HOST_WIDE_INT a, HOST_WIDE_INT b, bool *overflow)
   return result;
 #endif
 }
+#endif /* ! __cplusplus */

 #endif /* ! GCC_HWINT_H */


and the file is compiled using gcc (at least in stage1).

Looks like m2/Make-lang.in uses it's own definition HOSTCC to build these
files.  So maybe define a HOSTCXX and build with that instead?  There's also a
macro CPLUS which is unused.

However, these macros should be taken from the parent Makefile, so maybe just
use CC and CXX instead?

Trying
--- a/gcc/m2/Make-lang.in
+++ b/gcc/m2/Make-lang.in
@@ -32,7 +32,7 @@
 GM2_1 = ./gm2 -B./stage1/m2 -g -fm2-g
 XGCC = ./xgcc -B./
 GM2_2 = ./gm2 -B./stage2/m2 -g -fm2-g
-HOSTCC = gcc
+HOSTCC = $(CXX)
 CFLAGS=-g   ## remove this
 LDLAGS=-g   ## remove this

doesn't work, gm2 isn't yet C++ ready.

Jakub confirmed on irc:
<jakub> compiling with hwint.h includes with C is not supported anymore...