cargo: Fix crate name VS package name VS dependency name confusion

If dependency name does not match the package name, we have to rename
the crate name to the dependency name. Yes, that makes 3 different names
for the same dependency, good job cargo! For example:
- package name: cairo-sys-rs
- crate name: cairo-sys
- dependency name: ffi

mesonbuild/cargo/interpreter.py

@@ -20,7 +20,7 @@
 import collections
 import typing as T
 
 from functools import lru_cache
 from pathlib import Path
 
 from . import builder
@@ -646,6 +646,20 @@
             build.method('get', build.identifier('features'), [build.string(name), build.bool(False)]),
         )
 
+    # If dependency name does not match the package name, we have to rename the
+    # crate name to the dependency name. Yes, that makes 3 different names for
+    # the same dependency, good job cargo! For example:
+    # - package name: cairo-sys-rs
+    # - crate name: cairo-sys
+    # - dependency name: ffi
+    # rust_dependency_map += {xxx_dep.get_variable('crate-name'): 'name'}
+    rust_dependency_map_ast = []
+    if name != dep.package:
+        rust_dependency_map_ast.append(
+            build.plusassign(build.dict({
+                build.method('get_variable', build.identifier(_dependency_varname(dep.package)), [build.string('crate-name')]): build.string(name),
+            }), 'rust_dependency_map'))
+
     # Lookup for this dependency with the features we want in default_options kwarg.
     #
     # However, this subproject could have been previously configured with a
@@ -712,13 +726,17 @@
                     ])
                 ]))
             ])),
+            *rust_dependency_map_ast,
         ])),
     ])
+
     return ast
 
 
 def _create_dependencies(cargo: Manifest, build: builder.Builder) -> T.List[mparser.BaseNode]:
-    ast: T.List[mparser.BaseNode] = []
+    ast: T.List[mparser.BaseNode] = [
+        build.assign(build.dict({}), 'rust_dependency_map'),
+    ]
     for condition, dependencies in cargo.target.items():
         ifblock: T.List[mparser.BaseNode] = []
         elseblock: T.List[mparser.BaseNode] = []
@@ -748,13 +766,10 @@
 
 def _create_lib(cargo: Manifest, build: builder.Builder, crate_type: manifest.CRATE_TYPE) -> T.List[mparser.BaseNode]:
     dependencies: T.List[mparser.BaseNode] = []
-    dependency_map: T.Dict[mparser.BaseNode, mparser.BaseNode] = {}
     deps_i = [cargo.dependencies.items()]
     deps_i += [deps.items() for deps in cargo.target.values()]
     for name, dep in itertools.chain.from_iterable(deps_i):
         dependencies.append(build.identifier(_dependency_varname(dep.package)))
-        if name != dep.package:
-            dependency_map[build.string(fixup_meson_varname(dep.package))] = build.string(name)
     for name, dep in cargo.system_dependencies.items():
         dependencies.append(build.identifier(f'{fixup_meson_varname(name)}_system_dep'))
 
@@ -765,14 +780,15 @@
 
     dependencies.append(build.identifier(_extra_deps_varname()))
 
+    crate_name = cargo.lib.name or cargo.package.name
     posargs: T.List[mparser.BaseNode] = [
-        build.string(fixup_meson_varname(cargo.package.name)),
+        build.string(fixup_meson_varname(crate_name)),
         build.string(cargo.lib.path),
     ]
 
     kwargs: T.Dict[str, mparser.BaseNode] = {
         'dependencies': build.array(dependencies),
-        'rust_dependency_map': build.dict(dependency_map),
+        'rust_dependency_map': build.identifier('rust_dependency_map'),
         'rust_args': build.array(rust_args),
     }
 
@@ -816,6 +832,7 @@
                     'link_with': build.identifier('lib'),
                     'variables': build.dict({
                         build.string('features'): build.method('join', build.string(','), [build.method('keys', build.identifier('features'))]),
+                        build.string('crate-name'): build.string(crate_name),
                     })
                 },
             ),