Deduplicate export-dynamic and pthread. Closes #4567.

mesonbuild/backend/ninjabackend.py

@@ -2442,7 +2442,7 @@ rule FORTRAN_DEP_HACK%s
             for dep in target.get_external_deps():
                 # Extend without reordering or de-dup to preserve `-L -l` sets
                 # https://github.com/mesonbuild/meson/issues/1718
-                commands.extend_direct(dep.get_link_args())
+                commands.extend_preserving_lflags(dep.get_link_args())
                 need_threads |= dep.need_threads()
                 need_openmp |= dep.need_openmp()
             for d in target.get_dependencies():
@@ -2450,7 +2450,7 @@ rule FORTRAN_DEP_HACK%s
                     for dep in d.get_external_deps():
                         need_threads |= dep.need_threads()
                         need_openmp |= dep.need_openmp()
-                        commands.extend_direct(dep.get_link_args())
+                        commands.extend_preserving_lflags(dep.get_link_args())
             if need_openmp:
                 commands += linker.openmp_flags()
             if need_threads:

mesonbuild/compilers/compilers.py

@@ -612,7 +612,10 @@ class CompilerArgs(list):
     dedup2_suffixes = ()
     dedup2_args = ()
     # Arg prefixes and args that must be de-duped by returning 1
-    dedup1_prefixes = ('-l', '-Wl,-l')
+    #
+    # NOTE: not thorough. A list of potential corner cases can be found in
+    # https://github.com/mesonbuild/meson/pull/4593#pullrequestreview-182016038
+    dedup1_prefixes = ('-l', '-Wl,-l', '-Wl,--export-dynamic')
     dedup1_suffixes = ('.lib', '.dll', '.so', '.dylib', '.a')
     # Match a .so of the form path/to/libfoo.so.0.1.0
     # Only UNIX shared libraries require this. Others have a fixed extension.
@@ -748,6 +751,17 @@ class CompilerArgs(list):
         for elem in iterable:
             self.append_direct(elem)
 
+    def extend_preserving_lflags(self, iterable):
+        normal_flags = []
+        lflags = []
+        for i in iterable:
+            if i.startswith('-l') or i.startswith('-L'):
+                lflags.append(i)
+            else:
+                normal_flags.append(i)
+        self.extend(normal_flags)
+        self.extend_direct(lflags)
+
     def __add__(self, args):
         new = CompilerArgs(self, self.compiler)
         new += args

run_unittests.py

@@ -118,6 +118,21 @@ def skipIfNoPkgconfig(f):
         return f(*args, **kwargs)
     return wrapped
 
+def skipIfNoPkgconfigDep(depname):
+    '''
+    Skip this test if the given pkg-config dep is not found, unless we're on CI.
+    '''
+    def wrapper(func):
+        @functools.wraps(func)
+        def wrapped(*args, **kwargs):
+            if not is_ci() and shutil.which('pkg-config') is None:
+                raise unittest.SkipTest('pkg-config not found')
+            if not is_ci() and subprocess.call(['pkg-config', '--exists', depname]) != 0:
+                raise unittest.SkipTest('pkg-config dependency {} not found.'.format(depname))
+            return func(*args, **kwargs)
+        return wrapped
+    return wrapper
+
 def skip_if_not_language(lang):
     def wrapper(func):
         @functools.wraps(func)
@@ -4393,6 +4408,19 @@ endian = 'little'
     def test_install_subdir_symlinks_with_default_umask_and_mode(self):
         self.install_subdir_invalid_symlinks('196 install_mode', 'sub1')
 
+    @skipIfNoPkgconfigDep('gmodule-2.0')
+    def test_ldflag_dedup(self):
+        testdir = os.path.join(self.unit_test_dir, '49 ldflagdedup')
+        if is_cygwin() or is_osx():
+            raise unittest.SkipTest('Not applicable on Cygwin or OSX.')
+        self.init(testdir)
+        build_ninja = os.path.join(self.builddir, 'build.ninja')
+        max_count = 0
+        search_term = '-Wl,--export-dynamic'
+        with open(build_ninja, 'r', encoding='utf-8') as f:
+            for line in f:
+                max_count = max(max_count, line.count(search_term))
+        self.assertEqual(max_count, 1, 'Export dynamic incorrectly deduplicated.')
 
 class LinuxCrossArmTests(BasePlatformTests):
     '''

test cases/unit/49 ldflagdedup/bob.c

@@ -0,0 +1,5 @@
+#include<gmodule.h>
+
+int func() {
+    return 0;
+}

test cases/unit/49 ldflagdedup/meson.build

@@ -0,0 +1,12 @@
+project('lddedup', 'c')
+
+# Chosen because its ldflags contains -Wl,--export-dynamic,
+# which must be deduplicated.
+gm = dependency('gmodule-2.0')
+
+lib = static_library('bob', 'bob.c',
+  dependencies: gm)
+
+executable('prog', 'prog.c',
+  link_with: lib,
+  dependencies: gm)

test cases/unit/49 ldflagdedup/prog.c

@@ -0,0 +1,7 @@
+#include<gmodule.h>
+
+int func();
+
+int main(int argc, char **argv) {
+    return func();
+}