build-sys: add UL_PROG_CLANG function, rename warnings.m4 -> compiler.m4

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/m4/compiler.m4 b/m4/compiler.m4
new file mode 100644
index 000000000..02e7af22a
--- /dev/null
+++ b/m4/compiler.m4
@@ -0,0 +1,62 @@
+dnl Copyright (C) 2008-2011 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.
+
+dnl From Simon Josefsson
+dnl -- derivated from coreutils m4/warnings.m4
+
+# UL_AS_VAR_APPEND(VAR, VALUE)
+# ----------------------------
+# Provide the functionality of AS_VAR_APPEND if Autoconf does not have it.
+m4_ifdef([AS_VAR_APPEND],
+[m4_copy([AS_VAR_APPEND], [UL_AS_VAR_APPEND])],
+[m4_define([UL_AS_VAR_APPEND],
+[AS_VAR_SET([$1], [AS_VAR_GET([$1])$2])])])
+
+# UL_WARN_ADD(PARAMETER, [VARIABLE = WARN_CFLAGS])
+# ------------------------------------------------
+# Adds parameter to WARN_CFLAGS if the compiler supports it.  For example,
+# UL_WARN_ADD([-Wparentheses]).
+AC_DEFUN([UL_WARN_ADD],
+dnl FIXME: ul_Warn must be used unquoted until we can assume
+dnl autoconf 2.64 or newer.
+[AS_VAR_PUSHDEF([ul_Warn], [ul_cv_warn_$1])dnl
+AC_CACHE_CHECK([whether compiler handles $1], m4_defn([ul_Warn]), [
+  ul_save_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="${CPPFLAGS} $1"
+  AC_PREPROC_IFELSE([AC_LANG_PROGRAM([])],
+                    [AS_VAR_SET(ul_Warn, [yes])],
+                    [AS_VAR_SET(ul_Warn, [no])])
+  CPPFLAGS="$ul_save_CPPFLAGS"
+])
+AS_VAR_IF(ul_Warn, [yes],
+  [UL_AS_VAR_APPEND(m4_if([$2], [], [[WARN_CFLAGS]], [[$2]]), [" $1"])])
+AS_VAR_POPDEF([ul_Warn])dnl
+m4_ifval([$2], [AS_LITERAL_IF([$2], [AC_SUBST([$2])], [])])dnl
+])
+
+
+# UL_PROG_CLANG
+# -------------
+# Checks if compiler is clang, defines compiler_clang=yes if yes
+AC_DEFUN([UL_PROG_CLANG], [
+  AC_REQUIRE([AC_PROG_CC])
+  AC_CACHE_CHECK([whether clang is in use], [ul_cv_clang], [
+    case ${CC} in #(
+      *gcc*)   ul_cv_clang=no ;;
+      *clang*) ul_cv_clang=yes ;;
+      *) AC_COMPILE_IFELSE([AC_LANG_SOURCE([int main() {
+           #ifdef __clang__
+               return 0;
+             #else
+               #error The __clang__ was not defined
+             #endif
+           }])],
+           [ul_cv_clang=yes],
+           [ul_cv_clang=no]
+         ) ;;
+    esac
+  ])
+  compiler_clang=$ul_cv_clang
+])