Use -Wtrailing-whitespace when warning

* configure.ac: When enabling GCC warnings, enable GCC 15’s new
-Wtrailing-whitespace option if available, as that’s the Emacs style.

(cherry picked from commit 589f596c96964ecf5e736a4b3b674ede4b193910)

diff --git a/configure.ac b/configure.ac
index 25454f54b105eacc3fde7bd3a8ae38a5d994d42c..f4c11655b98f63c46671a5925562e8e99ebba8f2 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1851,6 +1851,7 @@ AS_IF([test $gl_gcc_warnings = no],
     gl_WARN_ADD([$w])
   done
   gl_WARN_ADD([-Wredundant-decls])     # Prefer this, as we don't use Bison.
+  gl_WARN_ADD([-Wtrailing-whitespace]) # This project's coding style
   gl_WARN_ADD([-Wno-missing-field-initializers]) # We need this one
   gl_WARN_ADD([-Wno-override-init])    # More trouble than it is worth
   gl_WARN_ADD([-Wno-sign-compare])     # Too many warnings for now