From 46d7f9a7edf26d6d2fd70338a9b115f2596e7174 Mon Sep 17 00:00:00 2001
From: Jeff Squyres <jsquyres@cisco.com>
Date: Fri, 21 Jan 2005 13:53:48 +0000
Subject: [PATCH] Ensure that compilers that pretend to be gcc don't actually
 get the gcc-specific compiler flags (because they don't work -- @#$%@#$%!!!)

This commit was SVN r4092.
---
 config/ompi_setup_cc.m4  | 36 ++++++++++++++++++++++++++++++++++--
 config/ompi_setup_cxx.m4 | 39 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 70 insertions(+), 5 deletions(-)

diff --git a/config/ompi_setup_cc.m4 b/config/ompi_setup_cc.m4
index 3ceb06041b..bfc871f75e 100644
--- a/config/ompi_setup_cc.m4
+++ b/config/ompi_setup_cc.m4
@@ -39,6 +39,32 @@ AC_DEFINE_UNQUOTED(OMPI_CC, "$CC", [OMPI underlying C compiler])
 
 CPPFLAGS="$CPPFLAGS -DOMPI_BUILDING=1"
 
+# Check for compilers that impersonate gcc
+
+AC_MSG_CHECKING([for compilers that impersonate gcc])
+msg=
+TRULY_GCC=$GCC
+if test "$GCC" = "yes"; then
+    AC_TRY_COMPILE([], [
+int i = 3;
+#if __INTEL_COMPILER
+#error Yes, I am lying about being gcc.
+#endif
+], [], [msg=intel])
+
+    # If we made it through unscathed, then it really is gcc
+    if test -z "$msg"; then
+        TRULY_GCC=yes
+    else
+        TRULY_GCC=no
+    fi
+else
+    # We never thought that this was gcc to begin with
+    msg=not applicable
+    TRULY_GCC=no
+fi
+AC_MSG_RESULT([$msg])
+
 # Do we want debugging?
 
 if test "$WANT_DEBUG" = "1"; then
@@ -47,8 +73,11 @@ if test "$WANT_DEBUG" = "1"; then
     AC_MSG_WARN([-g has been added to CFLAGS (--enable-debug)])
 fi
 
+# These flags are generally gcc-specific; even the gcc-impersonating
+# compilers won't accept them.
+
 OMPI_CFLAGS_BEFORE_PICKY="$CFLAGS"
-if test "$GCC" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
+if test "$TRULY_GCC" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
     add="-Wall -Wundef -Wno-long-long -Wsign-compare"
     add="$add -Wmissing-prototypes -Wstrict-prototypes"
     add="$add -Wcomment -pedantic"
@@ -68,7 +97,7 @@ if test "$GCC" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
 fi
 
 # See if this version of gcc allows -finline-functions and/or
-# -fno-strict-aliasing
+# -fno-strict-aliasing.  Even check the gcc-impersonating compilers.
 if test "$GCC" = "yes"; then
     CFLAGS_orig="$CFLAGS"
 
@@ -124,6 +153,9 @@ fi
 # prohibitive).  If we're using anything else, be conservative and
 # just use -O.  
 
+# Note: gcc-imperonating compilers accept -O3, so there's no need for
+# $TRULY_GCC here.
+
 if test "$GCC" = yes; then
     OPTFLAGS="-O3"
 else
diff --git a/config/ompi_setup_cxx.m4 b/config/ompi_setup_cxx.m4
index 4a41b5a0de..a158b145ee 100644
--- a/config/ompi_setup_cxx.m4
+++ b/config/ompi_setup_cxx.m4
@@ -27,6 +27,32 @@ BASECXX="`basename $CXX`"
 CXXFLAGS="$ompi_cxxflags_save"
 AC_DEFINE_UNQUOTED(OMPI_CXX, "$CXX", [OMPI underlying C++ compiler])
 
+# Check for compilers that impersonate g++
+
+AC_MSG_CHECKING([for compilers that impersonate g++])
+msg=
+TRULY_GXX=$GXX
+if test "$GXX" = "yes"; then
+    AC_TRY_COMPILE([], [
+int i = 3;
+#if __INTEL_COMPILER
+#error Yes, I am lying about being g++.
+#endif
+], [], [msg=intel])
+
+    # If we made it through unscathed, then it really is g++   
+    if test -z "$msg"; then
+        TRULY_GXX=yes
+    else
+        TRULY_GXX=no
+    fi
+else
+    # We never thought that this was GXX to begin with
+    msg=not applicable
+    TRULY_GXX=no
+fi
+AC_MSG_RESULT([$msg])
+
 # Do we want debugging?
 
 if test "$WANT_DEBUG" = "1"; then
@@ -35,8 +61,11 @@ if test "$WANT_DEBUG" = "1"; then
     AC_MSG_WARN([-g has been added to CXXFLAGS (--enable-debug)])
 fi
 
+# These flags are generally g++-specific; even the g++-impersonating
+# compilers won't accept them.
+
 OMPI_CXXFLAGS_BEFORE_PICKY="$CXXFLAGS"
-if test "$GCC" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
+if test "$TRULY_GXX" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
     add="-g -Wall -Wundef -Wno-long-long"
 
     # see if -Wno-long-double works...
@@ -53,8 +82,9 @@ if test "$GCC" = "yes" -a "$WANT_PICKY_COMPILER" = 1; then
     unset add
 fi
 
-# See if this version of gcc allows -finline-functions
-if test "$GCC" = "yes"; then
+# See if this version of g++ allows -finline-functions
+
+if test "$GXX" = "yes"; then
     CXXFLAGS_orig="$CXXFLAGS"
     CXXFLAGS="$CXXFLAGS -finline-functions"
     add=
@@ -122,6 +152,9 @@ esac
 
 # Same rationale for g++ as with gcc in OMPI_SETUP_CC.
 
+# Note: gcc-imperonating compilers accept -O3, so there's no need for
+# $TRULY_GCC here.
+
 if test "$GXX" = yes; then
     OPTFLAGS="-O3"
 else