ninjabackend: rust: record Apple frameworks in rlibs

When rustc builds an rlib, it records -l and -L flags in the rlib's
metadata. Then when the final binary links against that rlib, rustc
knows what native libraries are needed.

Right now, frameworks are passed via -Clink-arg=-F and
-Clink-arg=-framework, which just passes raw flags to the linker. So
if an rlib depends on a framework and is installed, that information is
lost and cargo will fail to produce binaries from the rlib.

Fixes: #10725

mesonbuild/backend/ninjabackend.py

@@ -32,7 +32,7 @@ from ..mesonlib import (
     File, LibType, MachineChoice, MesonBugException, MesonException, OrderedSet, PerMachine,
     ProgressBar, quote_arg, unique_list
 )
-from ..mesonlib import get_compiler_for_source, has_path_sep, is_parent_path
+from ..mesonlib import get_compiler_for_source, has_path_sep, is_parent_path, lookbehind
 from ..options import OptionKey
 from .backends import CleanTrees
 from ..build import GeneratedList, InvalidArguments
@@ -2151,10 +2151,21 @@ class NinjaBackend(backends.Backend):
                 args.append(f'-Clink-arg={lib}')
 
         for e in external_deps:
-            for a in e.get_link_args():
-                if a.startswith('-L'):
+            prev: T.Optional[str] = None
+            for prev, a in lookbehind(e.get_link_args()):
+                if prev == '-framework':
+                    args.append(f'-lframework={a}')
+                    continue
+                elif a.startswith('-L'):
                     args.append(a)
                     continue
+                elif a.startswith('-F'):
+                    path = a[2:]
+                    args.append(f'-Lframework={path}')
+                    continue
+                elif a == '-framework':
+                    # handled once the framework name is available
+                    continue
                 elif is_library(a):
                     if isinstance(target, build.StaticLibrary):
                         static = a.endswith(('.a', '.lib'))

mesonbuild/utils/universal.py

@@ -139,6 +139,7 @@ __all__ = [
     'listify',
     'listify_array_value',
     'lookahead',
+    'lookbehind',
     'partition',
     'path_is_in_root',
     'pickle_load',
@@ -2536,6 +2537,24 @@ def get_subproject_dir(directory: str = '.') -> T.Optional[str]:
     return intr.extract_subproject_dir() or 'subprojects'
 
 
+def lookbehind(it_: T.Iterable[_T]) -> T.Iterator[T.Tuple[T.Optional[_T], _T]]:
+    """Get the current value of the iterable, and the previous if possible.
+
+    :param iter: The iterable to look into
+    :yield: A tuple of the previous value if possible, and the current one
+    :return: nothing
+    """
+    prev: T.Optional[_T] = None
+    it: T.Iterator[_T] = iter(it_)
+    while True:
+        try:
+            current = next(it)
+            yield prev, current
+            prev = current
+        except StopIteration:
+            break
+
+
 def lookahead(it_: T.Iterable[_T]) -> T.Iterator[T.Tuple[_T, T.Optional[_T]]]:
     """Get the current value of the iterable, and the next if possible.
 

test cases/rust/35 apple framework/lib.rs

@@ -0,0 +1,7 @@
+extern "C" {
+    fn CFAbsoluteTimeGetCurrent() -> f64;
+}
+
+pub fn get_absolute_time() -> f64 {
+    unsafe { CFAbsoluteTimeGetCurrent() }
+}

test cases/rust/35 apple framework/main.rs

@@ -0,0 +1,6 @@
+extern crate timelib;
+
+fn main() {
+    let time = timelib::get_absolute_time();
+    println!("Current CFAbsoluteTime: {}", time);
+}

test cases/rust/35 apple framework/meson.build

@@ -0,0 +1,13 @@
+project('rust apple framework', ['c', 'rust'], meson_version: '>=1.3.0')
+
+if host_machine.system() != 'darwin'
+  error('MESON_SKIP_TEST: this test is only for macOS')
+endif
+
+foundation = dependency('appleframeworks', modules: 'Foundation')
+
+timelib = static_library('timelib', 'lib.rs', dependencies: foundation, rust_abi: 'rust')
+alias_target('timelib', timelib)
+
+exe = executable('main', 'main.rs', link_with: timelib)
+test('main', exe)

unittests/darwintests.py

@@ -174,3 +174,23 @@ class DarwinTests(BasePlatformTests):
         # Those RPATHs are no longer valid and should not be present after installation
         rpaths = self._get_darwin_rpaths(os.path.join(self.installdir, 'usr/lib/libbar.dylib'))
         self.assertListEqual(rpaths, [])
+
+    @skip_if_not_language('rust')
+    def test_rust_apple_framework_rlib(self):
+        '''
+        Test that Rust rlibs properly record Apple framework dependencies,
+        so that external tools (like cargo) can link against them without
+        meson's help.
+        '''
+        testdir = os.path.join(self.rust_test_dir, '35 apple framework')
+        self.init(testdir)
+        # Build only the library, not the executable
+        self.build(target='timelib')
+        # Manually invoke rustc to build the executable, using the rlib.
+        # This simulates what cargo or another build system would do.
+        rlib = os.path.join(self.builddir, 'libtimelib.rlib')
+        main_rs = os.path.join(testdir, 'main.rs')
+        out_exe = os.path.join(self.builddir, 'manual_main')
+        subprocess.check_call(['rustc', '--extern', f'timelib={rlib}', main_rs, '-o', out_exe])
+        # Run the executable to verify it works
+        subprocess.check_call([out_exe])