On 06/04/16 11:01 +0200, Jakub Jelinek wrote:
On Wed, Apr 06, 2016 at 09:50:48AM +0100, Jonathan Wakely wrote:On 06/04/16 09:39 +0200, Eric Botcazou wrote: >we recently ran into build failures on Windows systems using a somewhat old >grep, coming from a syntax error in the libstdc++-symbols.ver version file: > ># Symbol versioning for shared libraries. >if ENABLE_SYMVERS >libstdc++-symbols.ver: ${glibcxx_srcdir}/$(SYMVER_FILE) \ > $(port_specific_symbol_files) > cp ${glibcxx_srcdir}/$(SYMVER_FILE) $@.tmp > chmod +w $@.tmp > if test "x$(port_specific_symbol_files)" != x; then \ > if grep '^# Appended to version file.' \ > $(port_specific_symbol_files) /dev/null > /dev/null 2>&1; then >\ > cat $(port_specific_symbol_files) >> $@.tmp; \ > else \ > sed -n '1,/DO NOT DELETE/p' $@.tmp > tmp.top; \ > sed -n '/DO NOT DELETE/,$$p' $@.tmp > tmp.bottom; \ > cat tmp.top $(port_specific_symbol_files) tmp.bottom > $@.tmp; \ > rm tmp.top tmp.bottom; \ > fi; \ > fi > >Note the double /dev/null on the grep command line. The first one causes the >grep to fail when the command is invoked on these systems. That's old code, >but it is now invoked for config/abi/pre/float128.ver on the mainline and 5 >branch and this breaks the build on these systems (4.9 builds fine). > >This first /dev/null doesn't serve any useful purpose and seems to be a typo,Doesn't it mean that if $port_specific_symbol_files contains only whitespace we don't hang waiting for input from stdin? The 'if' above it will be true when "x$port_specific_symbol_files" = "x " or similar. I don't see any way for that to happen in the FSF tree, so it should be safe. I'm a bit concerned about making that change this late in stage 4 though. There isn't much time to find out if it breaks an obscure target.As it is a make variable, can't make be used to test this? So perhaps chmod +w $@.tmp ifneq ($(port_specific_symbol_files),) if grep '^# Appended to version file.' \ $(port_specific_symbol_files) /dev/null > /dev/null 2>&1; then \ cat $(port_specific_symbol_files) >> $@.tmp; \ else \ sed -n '1,/DO NOT DELETE/p' $@.tmp > tmp.top; \ sed -n '/DO NOT DELETE/,$$p' $@.tmp > tmp.bottom; \ cat tmp.top $(port_specific_symbol_files) tmp.bottom > $@.tmp; \ rm tmp.top tmp.bottom; \ fi; endif ? Though, I think the initial and trailing whitespace is removed during expansion (or already parsing of the vars), so even the test "x$(port_specific_symbol_files)" != x check should work right.
OK, I have no objection to the original patch then.
