Implement rustc controlled whole-archive linking

Rustc as of version 1.61.0 has support for controlling when
whole-archive linking takes place, previous to this it tried to make a
good guess about what you wanted, which worked most of the time. This is
now implemented.

Additionally, rustc makes some assumptions about library names
(specifically static names), that meson does not keep. This can be fixed
with rustc 1.67, where a new +verbatim modifier has been added. We can
then force rustc to use the name we give it. Before that, we can sneak
through `/WHOELARCHIVE:` in cases of dynamic linking (into a dll or
exe), but we can't force the archiver to do what we want (rustc
considers the archiver to be an implementation detail). The only
solution I can come up with is to copy the library to the format that
rustc expects. I've run into some issues with that as well, so we warn
in that case.

The decisions to leave static into static broken on MSVC for 1.61–1.66
was made because:

 1) The work around is non-trivial, and we would have to support that
    workaround for a long time
 2) The number of users of Rust in Meson is small
 3) The number of users of Rust in Meson on Windows, with MSVC is tiny
 4) Using rustup to update rustc on windows is trivial, and solves the
    problem completely

Fixes: #10723
Fixes: #11247

Co-authored-by: Nirbheek Chauhan <nirbheek@centricular.com>

mesonbuild/backend/ninjabackend.py

@@ -1901,7 +1901,8 @@ def generate_rust_target(self, target: build.BuildTarget) -> None:
         args += output
         linkdirs = mesonlib.OrderedSet()
         external_deps = target.external_deps.copy()
-        for d in itertools.chain(target.link_targets, target.link_whole_targets):
+        # TODO: we likely need to use verbatim to handle name_prefix and name_suffix
+        for d in target.link_targets:
             linkdirs.add(d.subdir)
             if d.uses_rust():
                 # specify `extern CRATE_NAME=OUTPUT_FILE` for each Rust
@@ -1922,6 +1923,55 @@ def generate_rust_target(self, target: build.BuildTarget) -> None:
                 # Rust uses -l for non rust dependencies, but we still need to
                 # add dylib=foo
                 args += ['-l', f'dylib={d.name}']
+
+        # Since 1.61.0 Rust has a special modifier for whole-archive linking,
+        # before that it would treat linking two static libraries as
+        # whole-archive linking. However, to make this work we have to disable
+        # bundling, which can't be done until 1.63.0… So for 1.61–1.62 we just
+        # have to hope that the default cases of +whole-archive are sufficent.
+        # See: https://github.com/rust-lang/rust/issues/99429
+        if mesonlib.version_compare(rustc.version, '>= 1.63.0'):
+            whole_archive = ':+whole-archive,-bundle'
+        else:
+            whole_archive = ''
+
+        if mesonlib.version_compare(rustc.version, '>= 1.67.0'):
+            verbatim = ',+verbatim'
+        else:
+            verbatim = ''
+
+        for d in target.link_whole_targets:
+            linkdirs.add(d.subdir)
+            if d.uses_rust():
+                # specify `extern CRATE_NAME=OUTPUT_FILE` for each Rust
+                # dependency, so that collisions with libraries in rustc's
+                # sysroot don't cause ambiguity
+                args += ['--extern', '{}={}'.format(d.name, os.path.join(d.subdir, d.filename))]
+                project_deps.append(RustDep(d.name, self.rust_crates[d.name].order))
+            else:
+                if rustc.linker.id in {'link', 'lld-link'}:
+                    if verbatim:
+                        # If we can use the verbatim modifier, then everything is great
+                        args += ['-l', f'static{whole_archive}{verbatim}={d.get_outputs()[0]}']
+                    elif isinstance(target, build.StaticLibrary):
+                        # If we don't, for static libraries the only option is
+                        # to make a copy, since we can't pass objects in, or
+                        # directly affect the archiver. but we're not going to
+                        # do that given how quickly rustc versions go out of
+                        # support unless there's a compelling reason to do so.
+                        # This only affects 1.61–1.66
+                        mlog.warning('Due to limitations in Rustc versions 1.61–1.66 and meson library naming',
+                                     'whole-archive linking with MSVC may or may not work. Upgrade rustc to',
+                                     '>= 1.67. A best effort is being made, but likely won\'t work')
+                        args += ['-l', f'static={d.name}']
+                    else:
+                        # When doing dynamic linking (binaries and [c]dylibs),
+                        # we can instead just proxy the correct arguments to the linker
+                        for link_whole_arg in rustc.linker.get_link_whole_for([self.get_target_filename_for_linking(d)]):
+                            args += ['-C', f'link-arg={link_whole_arg}']
+                else:
+                    args += ['-l', f'static{whole_archive}={d.name}']
+                external_deps.extend(d.external_deps)
         for e in external_deps:
             for a in e.get_link_args():
                 if a.endswith(('.dll', '.so', '.dylib')):

test cases/rust/2 sharedlib/meson.build

@@ -1,10 +1,11 @@
-project('rust shared library', 'rust')
+project('rust shared library', 'rust', 'c')
 
 if host_machine.system() == 'darwin'
   error('MESON_SKIP_TEST: does not work right on macos, please fix!')
 endif
 
-l = shared_library('stuff', 'stuff.rs', install : true)
+s = static_library('static', 'value.c')
+l = shared_library('stuff', 'stuff.rs', link_whole : s, install : true)
 e = executable('prog', 'prog.rs', link_with : l, install : true)
 
 if build_machine.system() == 'windows'

test cases/rust/2 sharedlib/stuff.rs

@@ -1,3 +1,11 @@
 #![crate_name = "stuff"]
 
-pub fn explore() -> &'static str { "librarystring" }
+extern "C" {
+        fn c_value() -> i32;
+}
+
+pub fn explore() -> String {
+    unsafe {
+        format!("library{}string", c_value())
+    }
+}

test cases/rust/2 sharedlib/value.c

@@ -0,0 +1,3 @@
+int c_value(void) {
+    return 7;
+}

test cases/rust/3 staticlib/meson.build

@@ -1,5 +1,7 @@
-project('rust static library', 'rust')
+project('rust static library', 'rust', 'c')
 
-l = static_library('stuff', 'stuff.rs', install : true)
+o = static_library('other', 'other.rs')
+v = static_library('value', 'value.c')
+l = static_library('stuff', 'stuff.rs', link_whole : [o, v], install : true)
 e = executable('prog', 'prog.rs', link_with : l, install : true)
 test('linktest', e)

test cases/rust/3 staticlib/other.rs

@@ -0,0 +1,5 @@
+pub fn explore(
+    value: i32,
+) -> String {
+    format!("library{}string", value)
+}

test cases/rust/3 staticlib/prog.rs

@@ -1,3 +1,5 @@
 extern crate stuff;
 
-fn main() { println!("printing: {}", stuff::explore()); }
+fn main() {
+    println!("printing: {}", stuff::explore());
+}

test cases/rust/3 staticlib/stuff.rs

@@ -1,3 +1,14 @@
 #![crate_name = "stuff"]
 
-pub fn explore() -> &'static str { "librarystring" }
+extern crate other;
+
+extern "C" {
+    fn c_explore_value() -> i32;
+}
+
+pub fn explore(
+) -> String {
+    unsafe {
+        other::explore(c_explore_value())
+    }
+}

test cases/rust/3 staticlib/value.c

@@ -0,0 +1,5 @@
+int
+c_explore_value (void)
+{
+    return 42;
+}

test cases/rust/5 polyglot static/clib.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+void hello_from_rust(void);
+
+static void hello_from_c(void) {
+    printf("Hello from C!\n");
+}
+
+void hello_from_both(void) {
+    hello_from_c();
+    hello_from_rust();
+}

test cases/rust/5 polyglot static/meson.build

@@ -8,7 +8,8 @@ deps = [
 
 extra_winlibs = meson.get_compiler('c').get_id() in ['msvc', 'clang-cl'] ? ['userenv.lib', 'ws2_32.lib', 'bcrypt.lib'] : []
 
-l = static_library('stuff', 'stuff.rs', rust_crate_type : 'staticlib', install : true)
+r = static_library('stuff', 'stuff.rs', rust_crate_type : 'staticlib')
+l = static_library('clib', 'clib.c', link_with : r, install : true)
 e = executable('prog', 'prog.c',
                dependencies: deps,
                link_with : l,

test cases/rust/5 polyglot static/prog.c

@@ -1,8 +1,7 @@
 #include <stdio.h>
 
-void f();
+void hello_from_both();
 
 int main(void) {
-    printf("Hello from C!\n");
-    f();
+    hello_from_both();
 }

test cases/rust/5 polyglot static/stuff.rs

@@ -1,6 +1,6 @@
 #![crate_name = "stuff"]
 
 #[no_mangle]
-pub extern fn f() {
+pub extern "C" fn hello_from_rust() {
     println!("Hello from Rust!");
 }

test cases/rust/5 polyglot static/test.json

@@ -2,6 +2,6 @@
   "installed": [
     {"type": "exe", "file": "usr/bin/prog"},
     {"type": "pdb", "file": "usr/bin/prog"},
-    {"type": "file", "file": "usr/lib/libstuff.a"}
+    {"type": "file", "file": "usr/lib/libclib.a"}
   ]
 }