Re: [PATCH v2] Makefile: dedup archives in $(LIBS) so link recipes don't repeat them

>
> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> A handful of link recipes listed archive files twice: once explicitly
> via $(filter %.a,$^) and again implicitly through $(LIBS), which
> expanded to $(filter-out %.o,$(GITLIBS)) $(EXTLIBS). On macOS the
> linker warned about the duplicates:
>
>   ld: warning: ignoring duplicate libraries: 'libgit.a', 'target/release/libgitcore.a'
>
> Redefine $(LIBS) to list archive prerequisites from $^ first, then
> the rest of the library list with those archives filtered out so each
> appears only once.
>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>     Makefile: drop duplicate %.a from test-helper link rule
>
>     Redefine $(LIBS) to list archive prerequisites from $^ first, then the
>     rest of the library list to avoid brittleness in the future.
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2314%2FHaraldNordgren%2Fmakefile-test-helper-dedup-libs-v2
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2314/HaraldNordgren/makefile-test-helper-dedup-libs-v2
> Pull-Request: https://github.com/git/git/pull/2314
>
> Range-diff vs v1:
>
>  1:  f6166450b0 ! 1:  0ef442ea05 Makefile: drop duplicate %.a from link recipes
>      @@ Metadata
>       Author: Harald Nordgren <haraldnordgren@gmail.com>
>
>        ## Commit message ##
>      -    Makefile: drop duplicate %.a from link recipes
>      +    Makefile: dedup archives in $(LIBS) so link recipes don't repeat them
>
>      -    Three link recipes list archive files twice on the link line: once
>      -    via $(filter %.a,$^) and again through $(LIBS), which expands to
>      -    $(filter-out %.o,$(GITLIBS)) $(EXTLIBS). On macOS the linker warns
>      -    about the duplicates:
>      +    A handful of link recipes listed archive files twice: once explicitly
>      +    via $(filter %.a,$^) and again implicitly through $(LIBS), which
>      +    expanded to $(filter-out %.o,$(GITLIBS)) $(EXTLIBS). On macOS the
>      +    linker warned about the duplicates:
>
>             ld: warning: ignoring duplicate libraries: 'libgit.a', 'target/release/libgitcore.a'
>
>      -    Drop the redundant filter from the test-helper, fuzz-program, and
>      -    unit-test recipes so they match the pattern used by other link
>      -    recipes in the file.
>      +    Redefine $(LIBS) to list archive prerequisites from $^ first, then
>      +    the rest of the library list with those archives filtered out so each
>      +    appears only once.
>
>           Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
>
>        ## Makefile ##
>      +@@ Makefile: endif
>      + #
>      + # where we use it as a dependency. Since we also pull object files
>      + # from the dependency list, that would make each entry appear twice.
>      +-LIBS = $(filter-out %.o, $(GITLIBS)) $(EXTLIBS)
>      ++# Archives from $^ come first, then the rest with those archives
>      ++# filtered out so each appears only once.
>      ++LIBS = $(filter %.a,$^) $(filter-out $(filter %.a,$^),$(filter-out %.o,$(GITLIBS)) $(EXTLIBS))
>      +
>      + BASIC_CFLAGS += $(COMPAT_CFLAGS)
>      + LIB_OBJS += $(COMPAT_OBJS)
>       @@ Makefile: perf: all
>        t/helper/test-tool$X: $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS)) $(UNIT_TEST_DIR)/test-lib.o
>
>
>
>  Makefile | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index b31ecb0756..a828a66f28 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2503,7 +2503,9 @@ endif
>  #
>  # where we use it as a dependency. Since we also pull object files
>  # from the dependency list, that would make each entry appear twice.
> -LIBS = $(filter-out %.o, $(GITLIBS)) $(EXTLIBS)
> +# Archives from $^ come first, then the rest with those archives
> +# filtered out so each appears only once.
> +LIBS = $(filter %.a,$^) $(filter-out $(filter %.a,$^),$(filter-out %.o,$(GITLIBS)) $(EXTLIBS))
>
>  BASIC_CFLAGS += $(COMPAT_CFLAGS)
>  LIB_OBJS += $(COMPAT_OBJS)
> @@ -3392,7 +3394,7 @@ perf: all
>  t/helper/test-tool$X: $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS)) $(UNIT_TEST_DIR)/test-lib.o
>
>  t/helper/test-%$X: t/helper/test-%.o GIT-LDFLAGS $(GITLIBS)
> -       $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(filter %.a,$^) $(LIBS)
> +       $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
>
>  check-sha1:: t/helper/test-tool$X
>         t/helper/test-sha1.sh
> @@ -4015,13 +4017,13 @@ fuzz-all: $(FUZZ_PROGRAMS)
>  $(FUZZ_PROGRAMS): %: %.o oss-fuzz/dummy-cmd-main.o $(GITLIBS) GIT-LDFLAGS
>         $(QUIET_LINK)$(FUZZ_CXX) $(FUZZ_CXXFLAGS) -o $@ $(ALL_LDFLAGS) \
>                 -Wl,--allow-multiple-definition \
> -               $(filter %.o,$^) $(filter %.a,$^) $(LIBS) $(LIB_FUZZING_ENGINE)
> +               $(filter %.o,$^) $(LIBS) $(LIB_FUZZING_ENGINE)
>
>  $(UNIT_TEST_PROGS): $(UNIT_TEST_BIN)/%$X: $(UNIT_TEST_DIR)/%.o $(UNIT_TEST_OBJS) \
>         $(GITLIBS) GIT-LDFLAGS
>         $(call mkdir_p_parent_template)
>         $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
> -               $(filter %.o,$^) $(filter %.a,$^) $(LIBS)
> +               $(filter %.o,$^) $(LIBS)
>
>  GIT-TEST-SUITES: FORCE
>         @FLAGS='$(CLAR_TEST_SUITES)'; \
>
> base-commit: 9ac3f193c05c2237e2b14ebaa1149e9fc8a1abe0
> --
> gitgitgadget