Enhance Rust support

- Adds a `crate_type` kwarg to library targets, allowing the different
  types of Rust [linkage][1].
- Shared libraries use the `dylib` crate type by default, but can also
  be `cdylib`
- Static libraries use the `rlib` crate type by default, but can also
  be `staticlib`
- If any Rust target has shared library dependencies, add the
  appropriate linker arguments, including rpath for the sysroot of the
  Rust compiler

[1]: https://doc.rust-lang.org/reference/linkage.html

1 files changed, 22 insertions, 1 deletions

diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 40a05bf..5764b54 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -1157,8 +1157,10 @@ int dummy;
         args = ['--crate-type']
         if isinstance(target, build.Executable):
             cratetype = 'bin'
+        elif hasattr(target, 'crate_type'):
+            cratetype = target.crate_type
         elif isinstance(target, build.SharedLibrary):
-            cratetype = 'rlib'
+            cratetype = 'dylib'
         elif isinstance(target, build.StaticLibrary):
             cratetype = 'rlib'
         else:
@@ -1177,6 +1179,23 @@ int dummy;
             if d == '':
                 d = '.'
             args += ['-L', d]
+        has_shared_deps = False
+        for dep in target.get_dependencies():
+            if isinstance(dep, build.SharedLibrary):
+                has_shared_deps = True
+        if isinstance(target, build.SharedLibrary) or has_shared_deps:
+            # add prefer-dynamic if any of the Rust libraries we link
+            # against are dynamic, otherwise we'll end up with
+            # multiple implementations of crates
+            args += ['-C', 'prefer-dynamic']
+            # build the usual rpath arguments as well...
+            rpath_args = rustc.build_rpath_args(self.environment.get_build_dir(),
+                                                self.determine_rpath_dirs(target),
+                                                target.install_rpath)
+            # ... but then add rustc's sysroot to account for rustup
+            # installations
+            for rpath_arg in rpath_args:
+                args += ['-C', 'link-arg=' + rpath_arg + ':' + os.path.join(rustc.get_sysroot(), 'lib')]
         element = NinjaBuildElement(self.all_outputs, target_name, 'rust_COMPILER', relsrc)
         if len(orderdeps) > 0:
             element.add_orderdep(orderdeps)
@@ -1184,6 +1203,8 @@ int dummy;
         element.add_item('targetdep', depfile)
         element.add_item('cratetype', cratetype)
         element.write(outfile)
+        if isinstance(target, build.SharedLibrary):
+            self.generate_shsym(outfile, target)
 
     def swift_module_file_name(self, target):
         return os.path.join(self.get_target_private_dir(target),