Re: [PATCH v3 4/4] ld/testsuite: Add comprehensive PE COFF weak external tests

Oops I forgot to amend this commit with my testsuite changes exercising the issue with archives. Will have to submit a v4. But otherwise, the practical changes are good and I tested them thoroughly. Including the fix for gcc PR124263

Jun 23, 2026 5:38:29 PM Peter Damianov <[email protected]>:

> Add tests covering the full matrix of weak/strong symbol interactions
> for PE COFF weak externals, based on testcases by Martin Storsjo.
> The archive test covers PE weak externals whose public name is backed
> by a real fallback definition, and ensures weak declarations with the
> null fallback are not advertised as archive providers.
> 
> ld/testsuite/
> 
>     * ld-pe/pe-compile.exp (weak_ext_test): New proc.  Compiles
>     source files, links via gcc, and runs natively if possible.
>     (weak_ext_archive_test): New proc.
>     Add tests: normal, weak-undef, weak-defined,
>     weak-decl-weak-def, strong-undef-weak-def-archive, weak-use,
>     weak-override, weak-duplicate, weak-def-override, weak-def-use.
>     * ld-pe/weak-ext-main.c: New file.
>     * ld-pe/weak-ext-main-weak.c: New file.
>     * ld-pe/weak-ext-main-weak-def.c: New file.
>     * ld-pe/weak-ext-add2.c: New file.
>     * ld-pe/weak-ext-add1-weak-chained.c: New file.
>     * ld-pe/weak-ext-dummy.c: New file.
>     * ld-pe/weak-ext-expected1.c: New file.
>     * ld-pe/weak-ext-expected3.c: New file.
>     * ld-pe/weak-ext-expected5.c: New file.
>     * ld-pe/weak-ext-expected3-add1-weak.c: New file.
> ---
> ld/testsuite/ld-pe/pe-compile.exp             | 167 ++++++++++++++++++
> .../ld-pe/weak-ext-add1-weak-chained.c        |  13 ++
> ld/testsuite/ld-pe/weak-ext-add2.c            |   8 +
> ld/testsuite/ld-pe/weak-ext-dummy.c           |   5 +
> ld/testsuite/ld-pe/weak-ext-expected1.c       |   1 +
> .../ld-pe/weak-ext-expected3-add1-weak.c      |   9 +
> ld/testsuite/ld-pe/weak-ext-expected3.c       |   1 +
> ld/testsuite/ld-pe/weak-ext-expected5.c       |   1 +
> ld/testsuite/ld-pe/weak-ext-main-weak-def.c   |  26 +++
> ld/testsuite/ld-pe/weak-ext-main-weak.c       |  22 +++
> ld/testsuite/ld-pe/weak-ext-main.c            |  21 +++
> 11 files changed, 274 insertions(+)
> create mode 100644 ld/testsuite/ld-pe/weak-ext-add1-weak-chained.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-add2.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-dummy.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-expected1.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-expected3-add1-weak.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-expected3.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-expected5.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-main-weak-def.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-main-weak.c
> create mode 100644 ld/testsuite/ld-pe/weak-ext-main.c
> 
> diff --git a/ld/testsuite/ld-pe/pe-compile.exp b/ld/testsuite/ld-pe/pe-compile.exp
> index 041a1cb9344..aac8711dff2 100644
> --- a/ld/testsuite/ld-pe/pe-compile.exp
> +++ b/ld/testsuite/ld-pe/pe-compile.exp
> @@ -138,3 +138,170 @@ set align_tests {
> }
> 
> run_ld_link_tests $align_tests
> +
> +# Test PE COFF weak external symbol resolution.
> +# These tests cover the full matrix of weak/strong interactions to verify
> +# that the linker correctly resolves weak externals in PE COFF objects.
> +# Based on testcases by Martin Storsjo.
> +
> +proc weak_ext_test { testname sources } {
> +    global CC_FOR_TARGET
> +    global srcdir
> +    global subdir
> +
> +    set objfiles {}
> +    foreach src $sources {
> +   set fileroot [file rootname [file tail $src]]
> +   set obj "tmpdir/$fileroot.o"
> +   if ![ld_compile $CC_FOR_TARGET $srcdir/$subdir/$src $obj] {
> +       fail "$testname (compile $src)"
> +       return
> +   }
> +   lappend objfiles $obj
> +    }
> +
> +    set output "tmpdir/weak-ext-test.exe"
> +    if ![ld_link $CC_FOR_TARGET $output $objfiles] {
> +   fail "$testname (link)"
> +   return
> +    }
> +
> +    if ![isnative] {
> +   pass "$testname (link only)"
> +   return
> +    }
> +
> +    catch "exec $output" prog_output
> +    if { $prog_output eq "" } {
> +   pass $testname
> +    } else {
> +   verbose $prog_output
> +   fail "$testname ($prog_output)"
> +    }
> +}
> +
> +proc weak_ext_archive_test { } {
> +    global CC_FOR_TARGET
> +    global ar
> +    global nm
> +    global srcdir
> +    global subdir
> +
> +    set testname "weak external: archive strong undef + weak def"
> +    set main_obj "tmpdir/weak-ext-main.o"
> +    set weak_decl_obj "tmpdir/weak-ext-main-weak.o"
> +    set weak_obj "tmpdir/weak-ext-add1-weak-chained.o"
> +    set expected_obj "tmpdir/weak-ext-expected3.o"
> +    set weak_decl_archive "tmpdir/weak-ext-decl-archive.a"
> +    set archive "tmpdir/weak-ext-archive.a"
> +    set output "tmpdir/weak-ext-archive-test.exe"
> +
> +    set sources {weak-ext-main.c weak-ext-main-weak.c \
> +   weak-ext-add1-weak-chained.c weak-ext-expected3.c}
> +    set objects [list $main_obj $weak_decl_obj $weak_obj $expected_obj]
> +    foreach src $sources obj $objects {
> +   if ![ld_compile $CC_FOR_TARGET $srcdir/$subdir/$src $obj] {
> +       fail "$testname (compile $src)"
> +       return
> +   }
> +    }
> +
> +    set got [run_host_cmd "$ar" "rcs $weak_decl_archive $weak_decl_obj"]
> +    if ![string match "" $got] {
> +   fail "$testname (weak decl archive)"
> +   return
> +    }
> +
> +    # A weak declaration with the null fallback must not advertise its
> +    # public name as an archive-map provider.
> +    set got [run_host_cmd "$nm" "--print-armap $weak_decl_archive"]
> +    if [regexp "(^|\n)_?func in weak-ext-main-weak\\.o" $got] {
> +   verbose -log $got
> +   fail "$testname (weak decl armap)"
> +   return
> +    }
> +
> +    set got [run_host_cmd "$ar" "rcs $archive $weak_obj"]
> +    if ![string match "" $got] {
> +   fail "$testname (archive)"
> +   return
> +    }
> +
> +    # A weak external with a real fallback should advertise the public
> +    # alias, so a strong undefined reference can extract the member.
> +    set got [run_host_cmd "$nm" "--print-armap $archive"]
> +    if ![regexp "(^|\n)_?func in weak-ext-add1-weak-chained\\.o" $got] {
> +   verbose -log $got
> +   fail "$testname (armap)"
> +   return
> +    }
> +
> +    # Search the archive twice to cover command lines where the driver
> +    # adds a library implicitly and the user also names it explicitly.
> +    if ![ld_link $CC_FOR_TARGET $output \
> +        [list $main_obj $expected_obj $archive $archive]] {
> +   fail "$testname (link)"
> +   return
> +    }
> +
> +    if ![isnative] {
> +   pass "$testname (link only)"
> +   return
> +    }
> +
> +    catch "exec $output" prog_output
> +    if { $prog_output eq "" } {
> +   pass $testname
> +    } else {
> +   verbose $prog_output
> +   fail "$testname ($prog_output)"
> +    }
> +}
> +
> +# Strong undefined reference + strong definition: basic sanity check.
> +weak_ext_test "weak external: normal (strong undef + strong def)" \
> +    {weak-ext-main.c weak-ext-add2.c weak-ext-expected3.c weak-ext-dummy.c}
> +
> +# Weak declaration with no definition available: func remains NULL,
> +# never called.
> +weak_ext_test "weak external: weak undef (no def)" \
> +    {weak-ext-main-weak.c weak-ext-expected1.c weak-ext-dummy.c}
> +
> +# Weak declaration resolved by a strong definition in another object.
> +weak_ext_test "weak external: weak decl + strong def" \
> +    {weak-ext-main-weak.c weak-ext-add2.c weak-ext-expected3.c weak-ext-dummy.c}
> +
> +# Two weak externals for the same symbol meet: the one whose fallback
> +# alias points to an actual function body should win over the one whose
> +# fallback is NULL.
> +weak_ext_test "weak external: weak decl + weak def" \
> +    {weak-ext-main-weak.c weak-ext-add1-weak-chained.c weak-ext-expected3.c}
> +
> +# Strong undefined reference is seen before the weak definition: the
> +# linker must still store the weak external's aux record so the fallback
> +# alias can be resolved later.
> +weak_ext_test "weak external: strong undef + weak def" \
> +    {weak-ext-main.c weak-ext-add1-weak-chained.c weak-ext-expected3.c}
> +
> +weak_ext_archive_test
> +
> +# Strong definition overrides a weak definition: both call sites (in
> +# main and in dummy) should resolve to the strong def.
> +weak_ext_test "weak external: strong override of weak" \
> +    {weak-ext-main.c weak-ext-add1-weak-chained.c weak-ext-add2.c \
> +     weak-ext-expected5.c}
> +
> +# Two identical weak definitions for the same symbol: no conflict,
> +# the linker picks one (first wins) and discards the duplicate.
> +weak_ext_test "weak external: duplicate weak defs" \
> +    {weak-ext-main.c weak-ext-add1-weak-chained.c \
> +     weak-ext-expected3-add1-weak.c}
> +
> +# Weak definition in main overridden by a strong definition elsewhere.
> +weak_ext_test "weak external: weak def overridden by strong" \
> +    {weak-ext-main-weak-def.c weak-ext-add2.c weak-ext-expected3.c \
> +     weak-ext-dummy.c}
> +
> +# Weak definition in main used directly when no strong definition exists.
> +weak_ext_test "weak external: weak def used (no strong)" \
> +    {weak-ext-main-weak-def.c weak-ext-expected5.c weak-ext-dummy.c}
> diff --git a/ld/testsuite/ld-pe/weak-ext-add1-weak-chained.c b/ld/testsuite/ld-pe/weak-ext-add1-weak-chained.c
> new file mode 100644
> index 00000000000..5b68b8435e2
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-add1-weak-chained.c
> @@ -0,0 +1,13 @@
> +/* Weak definition of func (adds 1), plus dummy that calls func.  */
> +extern int value;
> +
> +__attribute__((weak)) void func (void)
> +{
> +  value += 1;
> +}
> +
> +void
> +dummy (void)
> +{
> +  func ();
> +}
> diff --git a/ld/testsuite/ld-pe/weak-ext-add2.c b/ld/testsuite/ld-pe/weak-ext-add2.c
> new file mode 100644
> index 00000000000..691554d17e3
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-add2.c
> @@ -0,0 +1,8 @@
> +/* Strong definition of func (adds 2).  */
> +extern int value;
> +
> +void
> +func (void)
> +{
> +  value += 2;
> +}
> diff --git a/ld/testsuite/ld-pe/weak-ext-dummy.c b/ld/testsuite/ld-pe/weak-ext-dummy.c
> new file mode 100644
> index 00000000000..1c97c3cf97f
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-dummy.c
> @@ -0,0 +1,5 @@
> +/* Empty dummy function.  */
> +void
> +dummy (void)
> +{
> +}
> diff --git a/ld/testsuite/ld-pe/weak-ext-expected1.c b/ld/testsuite/ld-pe/weak-ext-expected1.c
> new file mode 100644
> index 00000000000..5b4138b0bb1
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-expected1.c
> @@ -0,0 +1 @@
> +int expected = 1;
> diff --git a/ld/testsuite/ld-pe/weak-ext-expected3-add1-weak.c b/ld/testsuite/ld-pe/weak-ext-expected3-add1-weak.c
> new file mode 100644
> index 00000000000..585830bd304
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-expected3-add1-weak.c
> @@ -0,0 +1,9 @@
> +/* Second weak definition of func (adds 1) plus expected value.  */
> +extern int value;
> +
> +__attribute__((weak)) void func (void)
> +{
> +  value += 1;
> +}
> +
> +int expected = 3;
> diff --git a/ld/testsuite/ld-pe/weak-ext-expected3.c b/ld/testsuite/ld-pe/weak-ext-expected3.c
> new file mode 100644
> index 00000000000..3d67d70bcb0
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-expected3.c
> @@ -0,0 +1 @@
> +int expected = 3;
> diff --git a/ld/testsuite/ld-pe/weak-ext-expected5.c b/ld/testsuite/ld-pe/weak-ext-expected5.c
> new file mode 100644
> index 00000000000..fef6b322c03
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-expected5.c
> @@ -0,0 +1 @@
> +int expected = 5;
> diff --git a/ld/testsuite/ld-pe/weak-ext-main-weak-def.c b/ld/testsuite/ld-pe/weak-ext-main-weak-def.c
> new file mode 100644
> index 00000000000..05f81d189b4
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-main-weak-def.c
> @@ -0,0 +1,26 @@
> +/* Weak definition of func in main (adds 4).  */
> +#include <stdio.h>
> +
> +int value = 1;
> +
> +__attribute__((weak)) void func (void)
> +{
> +  value += 4;
> +}
> +
> +void dummy (void);
> +extern int expected;
> +
> +int
> +main (void)
> +{
> +  if (func)
> +    func ();
> +  dummy ();
> +  if (value != expected)
> +    {
> +      printf ("expected %d, got %d\n", expected, value);
> +      return 1;
> +    }
> +  return 0;
> +}
> diff --git a/ld/testsuite/ld-pe/weak-ext-main-weak.c b/ld/testsuite/ld-pe/weak-ext-main-weak.c
> new file mode 100644
> index 00000000000..bc1501f62c0
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-main-weak.c
> @@ -0,0 +1,22 @@
> +/* Weak declaration of func (no definition).  */
> +#include <stdio.h>
> +
> +__attribute__((weak)) void func (void);
> +void dummy (void);
> +
> +int value = 1;
> +extern int expected;
> +
> +int
> +main (void)
> +{
> +  if (func)
> +    func ();
> +  dummy ();
> +  if (value != expected)
> +    {
> +      printf ("expected %d, got %d\n", expected, value);
> +      return 1;
> +    }
> +  return 0;
> +}
> diff --git a/ld/testsuite/ld-pe/weak-ext-main.c b/ld/testsuite/ld-pe/weak-ext-main.c
> new file mode 100644
> index 00000000000..916bb246e5f
> --- /dev/null
> +++ b/ld/testsuite/ld-pe/weak-ext-main.c
> @@ -0,0 +1,21 @@
> +/* Strong undefined reference to func.  */
> +#include <stdio.h>
> +
> +void func (void);
> +void dummy (void);
> +
> +int value = 1;
> +extern int expected;
> +
> +int
> +main (void)
> +{
> +  func ();
> +  dummy ();
> +  if (value != expected)
> +    {
> +      printf ("expected %d, got %d\n", expected, value);
> +      return 1;
> +    }
> +  return 0;
> +}
> -- 
> 2.54.0