Re: ld_compile: force CFLAGS really necessary ?

[Mike Frysinger <vapier at gentoo dot org>]

On Tuesday 28 August 2007, Mike Frysinger wrote:
> i fetched binutils-2.18 and ran it through some `make check` only to find
> ld oddly failling some tests on me ... after digging through it a bit, it
> seems it's due to mixing of CFLAGS and CXXFLAGS.
>
> on my system, i throw -Wimplicit-function-declaration into my CFLAGS which
> does two things: (1) shows me implicit functions so i can send patches to
> fix code and (2) see when packages wrongly mix CFLAGS and CXXFLAGS.
>
> in ld/testsuite/lib/ld-lib.exp, the ld_compile function will append $CFLAGS
> to all commands given it.  this means even tests like ld-cdtest which
> compiles C++ code and which will cause erroneous failures when CFLAGS
> contains things that are not valid in CXXFLAGS.  doing a quick grep against
> ld_compile, i see CFLAGS is explicitly specified in the call to ld_compile
> by over half the tests which use this function ... and on my system, simply
> removing the CFLAGS append inside of the ld_compile function doesnt cause
> any regressions.
>
> so the question is, do we drop this auto CFLAGS append completely ?  or do
> we do a check against the suffix of $source and if it is set to .cc, auto
> append CXXFLAGS rather than CFLAGS ?

maybe something like the attached patch

2007-08-28  Mike Frysinger  <vapier@gentoo.org>

	* lib/ld-lib.exp (default_ld_compile): Pull in global CXXFLAGS and
	add it to $flags when $source matches *.cc.
	(run_ld_link_exec_tests): Pull in global CXXFLAGS and execute CXX
	with CXXFLAGS when $lang matches c++.
	(run_cc_link_tests): Likewise.
-mike

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2007-08-28  Mike Frysinger  <vapier@gentoo.org>

	* lib/ld-lib.exp (default_ld_compile): Pull in global CXXFLAGS and
	add it to $flags when $source matches *.cc.
	(run_ld_link_exec_tests): Pull in global CXXFLAGS and execute CXX
	with CXXFLAGS when $lang matches c++.
	(run_cc_link_tests): Likewise.

--- binutils-2.18/ld/testsuite/lib/ld-lib.exp
+++ binutils-2.18/ld/testsuite/lib/ld-lib.exp
@@ -206,6 +206,7 @@
 #
 proc default_ld_compile { cc source object } {
     global CFLAGS
+    global CXXFLAGS
     global srcdir
     global subdir
     global host_triplet
@@ -222,7 +223,11 @@
 
     catch "exec rm -f $object" exec_output
 
-    set flags "-I$srcdir/$subdir $CFLAGS"
+    if {[string match "*.cc" $source]} then {
+	set flags "-I$srcdir/$subdir $CXXFLAGS"
+    } else {
+	set flags "-I$srcdir/$subdir $CFLAGS"
+    }
 
     # If we are compiling with gcc, we want to add gcc_gas_flag to
     # flags.  Rather than determine this in some complex way, we guess
@@ -1287,6 +1287,7 @@
     global CC
     global CXX
     global CFLAGS
+    global CXXFLAGS
     global errcnt
     global exec_output
 
@@ -1321,7 +1322,11 @@
 	    # We ignore warnings since some compilers may generate
 	    # incorrect section attributes and the assembler will warn
 	    # them.
-	    ld_compile "$CC -c $CFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    if { [ string match "c++" $lang ] } {
+		ld_compile "$CXX -c $CXXFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    } else {
+		ld_compile "$CC -c $CFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    }
 
 	    # We have to use $CC to build PIE and shared library.
 	    if { [ string match "c" $lang ] } {
@@ -1413,6 +1418,7 @@
     global CC
     global CXX
     global CFLAGS
+    global CXXFLAGS
 
     foreach testitem $ldtests {
 	set testname [lindex $testitem 0]
@@ -1434,7 +1440,11 @@
 	    # We ignore warnings since some compilers may generate
 	    # incorrect section attributes and the assembler will warn
 	    # them.
-	    ld_compile "$CC -c $CFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    if { [ string match "c++" $lang ] } {
+		ld_compile "$CXX -c $CXXFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    } else {
+		ld_compile "$CC -c $CFLAGS $cflags" $srcdir/$subdir/$src_file $objfile
+	    }
 	}
 
 	# Clear error and warning counts.