New upstream version 1.9

[debian/gzip] / m4 / stdnoreturn.m4

diff --git a/m4/stdnoreturn.m4 b/m4/stdnoreturn.m4
new file mode 100644 (file)
index 0000000..a7ce376
--- /dev/null
+++ b/m4/stdnoreturn.m4
@@ -0,0 +1,51 @@
+# Check for stdnoreturn.h that conforms to C11.
+
+dnl Copyright 2012-2018 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Prepare for substituting <stdnoreturn.h> if it is not supported.
+
+AC_DEFUN([gl_STDNORETURN_H],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    cygwin*)
+      dnl Regardless whether a working <stdnoreturn.h> exists or not,
+      dnl we need our own <stdnoreturn.h>, because of the definition
+      dnl of _Noreturn done by gnulib-common.m4.
+      STDNORETURN_H='stdnoreturn.h'
+      ;;
+    *)
+      AC_CACHE_CHECK([for working stdnoreturn.h],
+        [gl_cv_header_working_stdnoreturn_h],
+        [AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <stdlib.h>
+                #include <stdnoreturn.h>
+                /* Do not check for 'noreturn' after the return type.
+                   C11 allows it, but it's rarely done that way
+                   and circa-2012 bleeding-edge GCC rejects it when given
+                   -Werror=old-style-declaration.  */
+                noreturn void foo1 (void) { exit (0); }
+                _Noreturn void foo2 (void) { exit (0); }
+                int testit (int argc, char **argv)
+                {
+                  if (argc & 1)
+                    return 0;
+                  (argv[0][0] ? foo1 : foo2) ();
+                }
+              ]])],
+           [gl_cv_header_working_stdnoreturn_h=yes],
+           [gl_cv_header_working_stdnoreturn_h=no])])
+      if test $gl_cv_header_working_stdnoreturn_h = yes; then
+        STDNORETURN_H=''
+      else
+        STDNORETURN_H='stdnoreturn.h'
+      fi
+      ;;
+  esac
+  AC_SUBST([STDNORETURN_H])
+  AM_CONDITIONAL([GL_GENERATE_STDNORETURN_H], [test -n "$STDNORETURN_H"])
+])