rust: Add linkdirs of indirect Rust dependencies to the target's link…

mesonbuild/backend/ninjabackend.py

@@ -1836,6 +1836,27 @@ def _get_rust_dependency_name(self, target: build.BuildTarget, dependency: LibTy
         # in Rust
         return target.rust_dependency_map.get(dependency.name, dependency.name).replace('-', '_')
 
+    def _add_rust_indirect_dependency_linkdirs(self, linkdirs: OrderedSet[str], dependency: LibTypes):
+        # Add all the linkdirs of indirect dependencies to the linkdirs if
+        # they're rlib/proc-macro/dylib dependencies. rustc requires this to
+        # be able to find the indirect dependencies during the build.
+        indirect_rust_deps = [dependency]
+
+        # Instead of actually recursing over the dependencies use a stack here
+        while indirect_rust_deps:
+            indirect_dep = indirect_rust_deps.pop()
+            if not indirect_dep.uses_rust() or indirect_dep.rust_crate_type in {'staticlib', 'cdylib'}:
+                continue
+            for d in indirect_dep.kwargs.get('dependencies', []):
+                if not hasattr(d, 'libraries'):
+                    continue
+                indirect_rust_deps += d.libraries
+                indirect_rust_deps += d.whole_libraries
+            indirect_rust_deps += indirect_dep.link_targets
+            indirect_rust_deps += indirect_dep.link_whole_targets
+
+            linkdirs.add(indirect_dep.subdir)
+
     def generate_rust_target(self, target: build.BuildTarget) -> None:
         rustc = target.compilers['rust']
         # Rust compiler takes only the main file as input and
@@ -1945,6 +1966,7 @@ def generate_rust_target(self, target: build.BuildTarget) -> None:
                 d_name = self._get_rust_dependency_name(target, d)
                 args += ['--extern', '{}={}'.format(d_name, os.path.join(d.subdir, d.filename))]
                 project_deps.append(RustDep(d_name, self.rust_crates[d.name].order))
+                self._add_rust_indirect_dependency_linkdirs(linkdirs, d)
             elif isinstance(d, build.StaticLibrary):
                 # Rustc doesn't follow Meson's convention that static libraries
                 # are called .a, and import libraries are .lib, so we have to
@@ -1984,6 +2006,7 @@ def generate_rust_target(self, target: build.BuildTarget) -> None:
                 d_name = self._get_rust_dependency_name(target, d)
                 args += ['--extern', '{}={}'.format(d_name, os.path.join(d.subdir, d.filename))]
                 project_deps.append(RustDep(d_name, self.rust_crates[d.name].order))
+                self._add_rust_indirect_dependency_linkdirs(linkdirs, d)
             else:
                 if rustc.linker.id in {'link', 'lld-link'}:
                     if verbatim:

test cases/rust/20 transitive dependencies/liba/lib.rs

@@ -0,0 +1,3 @@
+pub fn foo() -> i32 {
+    123
+}

test cases/rust/20 transitive dependencies/liba/meson.build

@@ -0,0 +1,5 @@
+liba = static_library('liba', 'lib.rs',
+  rust_crate_type : 'rlib',
+)
+
+liba_dep = declare_dependency(link_with : liba)

test cases/rust/20 transitive dependencies/libb/lib.rs

@@ -0,0 +1,3 @@
+pub fn bar() -> i32 {
+    2 * liba::foo()
+}

test cases/rust/20 transitive dependencies/libb/meson.build

@@ -0,0 +1,6 @@
+libb = static_library('libb', 'lib.rs',
+  rust_crate_type : 'rlib',
+  dependencies : [liba_dep],
+)
+
+libb_dep = declare_dependency(link_with : libb)

test cases/rust/20 transitive dependencies/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("{}", libb::bar());
+}

test cases/rust/20 transitive dependencies/meson.build

@@ -0,0 +1,12 @@
+project('transitive dependencies', 'rust',
+  version : '1.0.0',
+  meson_version : '>= 1.0.0',
+  default_options : ['rust_std=2018'],
+)
+
+subdir('liba')
+subdir('libb')
+
+main = executable('main', 'main.rs',
+  dependencies : [libb_dep],
+)