Building groff-1.24.0.rc2 on FreeBSD 15, I get this compilation error:
CXX src/roff/troff/env.o
In file included from ../src/roff/troff/env.cpp:28:
In file included from /usr/include/c++/v1/vector:325:
In file included from /usr/include/c++/v1/__format/formatter_bool.h:16:
In file included from /usr/include/c++/v1/__format/concepts.h:16:
In file included from /usr/include/c++/v1/__format/format_parse_context.h:16:
In file included from /usr/include/c++/v1/string_view:251:
In file included from /usr/include/c++/v1/compare:174:
In file included from /usr/include/c++/v1/cmath:327:
/usr/include/c++/v1/__math/special_functions.h:51:16: error: expected
unqualified-id
51 | if (!__math::isfinite(__H_n)) {
| ^
./lib/math.h:3018:4: note: expanded from macro 'isfinite'
3018 | (sizeof (x) == sizeof (long double) ? gl_isfinitel (x) : \
| ^
It was supposed to be fixed by the 2025-12-19 patch
"isfinite-no-c++: New module.". But gnulib's <math.h> is still overriding
isfinite with a macro.
This patch fixes it.
2026-01-27 Bruno Haible <[email protected]>
isfinite-no-c++: Make more C++ safe.
* lib/math.in.h (isfinite): In C++ mode, define as a template with three
instantiations, instead of as a macro.
diff --git a/lib/math.in.h b/lib/math.in.h
index 680e1c5347..210ac99cf3 100644
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -2466,11 +2466,18 @@ _GL_CXXALIASWARN (yn);
_GL_EXTERN_C int gl_isfinitef (float x);
_GL_EXTERN_C int gl_isfinited (double x);
_GL_EXTERN_C int gl_isfinitel (long double x);
-# undef isfinite
-# define isfinite(x) \
- (sizeof (x) == sizeof (long double) ? gl_isfinitel (x) : \
- sizeof (x) == sizeof (double) ? gl_isfinited (x) : \
- gl_isfinitef (x))
+# ifdef __cplusplus
+template <typename T> int isfinite (T);
+template <> inline int isfinite<float> (float x) { return gl_isfinitef (x); }
+template <> inline int isfinite<double> (double x) { return gl_isfinited (x); }
+template <> inline int isfinite<long double> (long double x) { return
gl_isfinitel (x); }
+# else
+# undef isfinite
+# define isfinite(x) \
+ (sizeof (x) == sizeof (long double) ? gl_isfinitel (x) : \
+ sizeof (x) == sizeof (double) ? gl_isfinited (x) : \
+ gl_isfinitef (x))
+# endif
# endif
# if @GNULIB_ISFINITE@ && defined __cplusplus
# if defined isfinite || defined GNULIB_NAMESPACE
