From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Tue, 2 Jun 2015 21:29:19 +0000 (+0100)
Subject: Respect user CXXFLAGS.
X-Git-Tag: 0.15~223
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=658b27b00a59ae5876d631d933bfbd85ef329f27;p=re2c

Respect user CXXFLAGS.

As automake manual (chapter 27.6 "Flag Variables Ordering") states,
CXXFLAGS is a user variable and should be left for users to override
C++ compiler flags. Thus we should leave CXXFLAGS as is and modify
AM_CXXFLAGS insted.
---

diff --git a/re2c/Makefile.am b/re2c/Makefile.am
index 2b87c6bc..a510b1d0 100644
--- a/re2c/Makefile.am
+++ b/re2c/Makefile.am
@@ -1,5 +1,6 @@
 # flags
 # do *not* add CXXFLAGS here, add them in configure.ac
+AM_CXXFLAGS = $(CXXFLAGSDEFAULT)
 BISONFLAGS = -y -d --no-lines
 RE2CFLAGS = -bi
 
diff --git a/re2c/configure.ac b/re2c/configure.ac
index a76725db..6a8dac0d 100644
--- a/re2c/configure.ac
+++ b/re2c/configure.ac
@@ -33,6 +33,9 @@ AC_PROG_INSTALL
 
 
 # checks for C++ compiler flags
+AC_SUBST(CXXFLAGSDEFAULT, [])
+# TRY_CXXFLAG (flag)
+# appends 'flag' to CXXFLAGSDEFAULT iff C++ compiler knows this flag
 AC_DEFUN([TRY_CXXFLAG], [
     AC_MSG_CHECKING([C++ compiler flag $1])
     AS_VAR_SET([CXXFLAGS_BACKUP], ["$CXXFLAGS"])
@@ -40,13 +43,14 @@ AC_DEFUN([TRY_CXXFLAG], [
     AC_LANG_PUSH([C++])
     AC_COMPILE_IFELSE(
         [AC_LANG_PROGRAM()],
-        [AS_VAR_SET([TRY_CXXFLAG_RESULT], [yes])],
         [
-            AS_VAR_SET([TRY_CXXFLAG_RESULT], [no])
-            AS_VAR_SET([CXXFLAGS], ["$CXXFLAGS_BACKUP"])
-        ]
+            AS_VAR_SET([TRY_CXXFLAG_RESULT], [yes])
+            AS_VAR_SET([CXXFLAGSDEFAULT], ["$CXXFLAGSDEFAULT $1"])
+        ],
+        [AS_VAR_SET([TRY_CXXFLAG_RESULT], [no])]
     )
     AC_LANG_POP([C++])
+    AS_VAR_SET([CXXFLAGS], ["$CXXFLAGS_BACKUP"])
     AC_MSG_RESULT([$TRY_CXXFLAG_RESULT])
 ])
 TRY_CXXFLAG([-W])