[PATCH] Makefile: drop duplicate %.a from link recipes

[PATCH] Makefile: drop duplicate %.a from link recipes

[Harald Nordgren via GitGitGadget]

From: Harald Nordgren <haraldnordgren@gmail.com>

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:

  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.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    Makefile: drop duplicate %.a from test-helper link rule

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2314%2FHaraldNordgren%2Fmakefile-test-helper-dedup-libs-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2314/HaraldNordgren/makefile-test-helper-dedup-libs-v1
Pull-Request: https://github.com/git/git/pull/2314

 Makefile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index b31ecb0756..309d1d1e74 100644
--- a/Makefile
+++ b/Makefile
@@ -3392,7 +3392,7 @@ 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 +4015,13 @@ 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: 1666c1265231b0bc5f613fbbf3f0a9896cdef76e
-- 
gitgitgadget

Re: [PATCH] Makefile: drop duplicate %.a from link recipes

[Junio C Hamano]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

>  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)

I think the reason why the pattern to use only the .o files among
the prerequisites and then use only the .a files among the same
prerequisites (both filters $^) is used here is to make sure that the
linker sees object files first before library archives, so that by
the time its left-to-right scan sees the first library archive, all
the missing symbols in the object files are known.  The above change
depends on LIBS being a strict superset of all the library archive
files ($GITLIBS in the current code, but that can be updated in the
future) listed as prerequisites for the rule, but there is nothing to
guarantee that, so it looks brittle.

Exact same comment applies to the other two rules touched by this patch.

Re: [PATCH] Makefile: drop duplicate %.a from link recipes

[Harald Nordgren]

On Thu, Jun 4, 2026 at 2:33 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> "Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
> >  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)
>
> I think the reason why the pattern to use only the .o files among
> the prerequisites and then use only the .a files among the same
> prerequisites (both filters $^) is used here is to make sure that the
> linker sees object files first before library archives, so that by
> the time its left-to-right scan sees the first library archive, all
> the missing symbols in the object files are known.  The above change
> depends on LIBS being a strict superset of all the library archive
> files ($GITLIBS in the current code, but that can be updated in the
> future) listed as prerequisites for the rule, but there is nothing to
> guarantee that, so it looks brittle.
>
> Exact same comment applies to the other two rules touched by this patch.

Hmm, there are other constructs like this that rely on $(LIBS) being a
superset of the archives, so the three rules changed here align with
the trend rather than introduce a new trend.

Not saying we shouldn't find a way to handle the overall brittleness.


Harald

Re: [PATCH] Makefile: drop duplicate %.a from link recipes

[Harald Nordgren]

Maybe we can do this to get around the brittleness for all ~10 places:

```
-LIBS = $(filter-out %.o, $(GITLIBS)) $(EXTLIBS)
+LIBS = $(filter %.a,$^) $(filter-out $(filter %.a,$^),$(filter-out
%.o,$(GITLIBS)) $(EXTLIBS))

 BASIC_CFLAGS += $(COMPAT_CFLAGS)
 LIB_OBJS += $(COMPAT_OBJS)
@@ -3392,7 +3395,7 @@ perf: all
 t/helper/test-tool$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 +4018,13 @@ 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)'; \
```


Harald

On Thu, Jun 4, 2026 at 9:06 AM Harald Nordgren <haraldnordgren@gmail.com> wrote:
>
> On Thu, Jun 4, 2026 at 2:33 AM Junio C Hamano <gitster@pobox.com> wrote:
> >
> > "Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:
> >
> > >  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)
> >
> > I think the reason why the pattern to use only the .o files among
> > the prerequisites and then use only the .a files among the same
> > prerequisites (both filters $^) is used here is to make sure that the
> > linker sees object files first before library archives, so that by
> > the time its left-to-right scan sees the first library archive, all
> > the missing symbols in the object files are known.  The above change
> > depends on LIBS being a strict superset of all the library archive
> > files ($GITLIBS in the current code, but that can be updated in the
> > future) listed as prerequisites for the rule, but there is nothing to
> > guarantee that, so it looks brittle.
> >
> > Exact same comment applies to the other two rules touched by this patch.
>
> Hmm, there are other constructs like this that rely on $(LIBS) being a
> superset of the archives, so the three rules changed here align with
> the trend rather than introduce a new trend.
>
> Not saying we shouldn't find a way to handle the overall brittleness.
>
>
> Harald

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

[Harald Nordgren via GitGitGadget]

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