[gentoo-dev] [PATCH] flag-o-matic.eclass: LDFLAGS stripping, take two

[gentoo-dev] [PATCH] flag-o-matic.eclass: LDFLAGS stripping, take two

[Michał Górny]

Hi, everyone.

I've just reverted the LDFLAGS stripping code I've committed earlier
because it failed hard with clang. Here's an updated patch set that
ensures that clang is going to work fine. Please review.

--
Best regards,
Michał Górny

[gentoo-dev] [PATCH 1/3] flag-o-matic.eclass: test-flag-PROG, refactor to reduce duplication

[Michał Górny]

---
 eclass/flag-o-matic.eclass | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/eclass/flag-o-matic.eclass b/eclass/flag-o-matic.eclass
index b2f3742b3ecf..0393a30b74c3 100644
--- a/eclass/flag-o-matic.eclass
+++ b/eclass/flag-o-matic.eclass
@@ -433,11 +433,15 @@ test-flag-PROG() {
 		# Use -c so we can test the assembler as well.
 		-c -o /dev/null
 	)
-	if "${cmdline[@]}" -x${lang} - </dev/null >/dev/null 2>&1 ; then
-		"${cmdline[@]}" "${flag}" -x${lang} - </dev/null >/dev/null 2>&1
+	if "${cmdline[@]}" -x${lang} - </dev/null &>/dev/null ; then
+		cmdline+=( "${flag}" -x${lang} - )
 	else
-		"${cmdline[@]}" "${flag}" -c -o /dev/null /dev/null >/dev/null 2>&1
+		# XXX: what's the purpose of this? does it even work with
+		# any compiler?
+		cmdline+=( "${flag}" -c -o /dev/null /dev/null )
 	fi
+
+	"${cmdline[@]}" </dev/null &>/dev/null
 }
 
 # @FUNCTION: test-flag-CC
-- 
2.14.0

[gentoo-dev] [PATCH 2/3] flag-o-matic.eclass: test-flag-PROG, ignore unused args in clang

[Michał Górny]

By default, clang considers unused arguments as error when -Werror is
used. Since flag tests are performed without linking, this causes all
tests for linker flags to fail inadvertently and all those flags
are stripped as a result.

While the correctness of passing unused flags is doubtful, silently
stripping them in a few random packages is certainly not the solution
to the problem, and also makes the results differ between gcc and clang.
To account for that, use clang's -Qunused-arguments option to silence
unused argument warnings.

To avoid wasting time on testing the compiler, just try passing
-Qunused-arguments every time a flag check fails. If clang is not used,
the additional call will fail just the same as the previous one (either
because of the original flag or because of -Qunused-arguments), so
the result will be the same.
---
 eclass/flag-o-matic.eclass   | 9 ++++++++-
 eclass/tests/flag-o-matic.sh | 5 +++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/eclass/flag-o-matic.eclass b/eclass/flag-o-matic.eclass
index 0393a30b74c3..79866e04a483 100644
--- a/eclass/flag-o-matic.eclass
+++ b/eclass/flag-o-matic.eclass
@@ -441,7 +441,14 @@ test-flag-PROG() {
 		cmdline+=( "${flag}" -c -o /dev/null /dev/null )
 	fi
 
-	"${cmdline[@]}" </dev/null &>/dev/null
+	if ! "${cmdline[@]}" </dev/null &>/dev/null; then
+		# -Werror makes clang bail out on unused arguments as well;
+		# try to add -Qunused-arguments to work-around that
+		# other compilers don't support it but then, it's failure like
+		# any other
+		cmdline+=( -Qunused-arguments )
+		"${cmdline[@]}" </dev/null &>/dev/null
+	fi
 }
 
 # @FUNCTION: test-flag-CC
diff --git a/eclass/tests/flag-o-matic.sh b/eclass/tests/flag-o-matic.sh
index 92c68b82c3c9..5e7ee354bf33 100755
--- a/eclass/tests/flag-o-matic.sh
+++ b/eclass/tests/flag-o-matic.sh
@@ -143,6 +143,11 @@ tbegin "test-flags-CC (gcc-valid but clang-invalid flags)"
 out=$(CC=clang test-flags-CC -finline-limit=1200)
 [[ $? -ne 0 && -z ${out} ]]
 ftend
+
+tbegin "test-flags-CC (unused flags w/clang)"
+out=$(CC=clang test-flags-CC -Wl,-O1)
+[[ $? -eq 0 && ${out} == "-Wl,-O1" ]]
+ftend
 fi
 
 texit
-- 
2.14.0

[gentoo-dev] [PATCH 3/3] flag-o-matic.eclass: Strip LDFLAGS unsupported by the C compiler, #621274

[Michał Górny]

Include LDFLAGS in the variables stripped by strip-unsupported-flags.
The code reuses the current functions for testing CC, and so only remove
LDFLAGS that are rejected by the C compiler and not the linker. This
solves the case of bug #621274 where LDFLAGS contained GCC-specific
-flto flag.
---
 eclass/flag-o-matic.eclass   | 3 +++
 eclass/tests/flag-o-matic.sh | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/eclass/flag-o-matic.eclass b/eclass/flag-o-matic.eclass
index 79866e04a483..4e3cfff5afd5 100644
--- a/eclass/flag-o-matic.eclass
+++ b/eclass/flag-o-matic.eclass
@@ -546,6 +546,9 @@ strip-unsupported-flags() {
 	export CXXFLAGS=$(test-flags-CXX ${CXXFLAGS})
 	export FFLAGS=$(test-flags-F77 ${FFLAGS})
 	export FCFLAGS=$(test-flags-FC ${FCFLAGS})
+	# note: this does not verify the linker flags but it is enough
+	# to strip invalid C flags which are much more likely, #621274
+	export LDFLAGS=$(test-flags-CC ${LDFLAGS})
 }
 
 # @FUNCTION: get-flag
diff --git a/eclass/tests/flag-o-matic.sh b/eclass/tests/flag-o-matic.sh
index 5e7ee354bf33..53af9f862c41 100755
--- a/eclass/tests/flag-o-matic.sh
+++ b/eclass/tests/flag-o-matic.sh
@@ -55,7 +55,7 @@ done <<<"
 
 tbegin "strip-unsupported-flags"
 strip-unsupported-flags
-[[ ${CFLAGS} == "" ]] && [[ ${CXXFLAGS} == "-z=2" ]]
+[[ ${CFLAGS} == "" ]] && [[ ${CXXFLAGS} == "-z=2" ]] && [[ ${LDFLAGS} == "" ]]
 ftend
 
 for var in $(all-flag-vars) ; do
-- 
2.14.0

Re: [gentoo-dev] [PATCH] flag-o-matic.eclass: LDFLAGS stripping, take two

[Michał Górny]

W dniu pią, 11.08.2017 o godzinie 17∶26 +0200, użytkownik Michał Górny
napisał:
> Hi, everyone.
> 
> I've just reverted the LDFLAGS stripping code I've committed earlier
> because it failed hard with clang. Here's an updated patch set that
> ensures that clang is going to work fine. Please review.
> 

Merged now.

-- 
Best regards,
Michał Górny