From 48a181866f9cb574d13f59f8d94983a1bc2f88ed Mon Sep 17 00:00:00 2001
From: Dylan Baker <dylan@pnwbakers.com>
Date: Thu, 17 Sep 2020 12:02:07 -0700
Subject: [PATCH] compilers/mixins/clang: Make type safe

---
 mesonbuild/compilers/compilers.py    |  8 ++++++++
 mesonbuild/compilers/mixins/clang.py | 21 ++++++++++++++++-----
 run_mypy.py                          |  1 +
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index edd1c5d6c..2f26002cf 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -1032,6 +1032,14 @@ class Compiler(metaclass=abc.ABCMeta):
     def attribute_check_func(self, name: str) -> str:
         raise EnvironmentException('{} does not support attribute checks'.format(self.id))
 
+    def get_pch_suffix(self) -> str:
+        raise EnvironmentException('{} does not support pre compiled headers'.format(self.id))
+
+    def get_pch_name(self, name: str) -> str:
+        raise EnvironmentException('{} does not support pre compiled headers'.format(self.id))
+
+    def get_pch_use_args(self, pch_dir: str, header: str) -> T.List[str]:
+        raise EnvironmentException('{} does not support pre compiled headers'.format(self.id))
 
 
 def get_args_from_envvars(lang: str,
diff --git a/mesonbuild/compilers/mixins/clang.py b/mesonbuild/compilers/mixins/clang.py
index 7525c1246..8d80751fb 100644
--- a/mesonbuild/compilers/mixins/clang.py
+++ b/mesonbuild/compilers/mixins/clang.py
@@ -23,8 +23,10 @@ from ...linkers import AppleDynamicLinker
 from .gnu import GnuLikeCompiler
 
 if T.TYPE_CHECKING:
+    from ...envconfig import MachineChoice
     from ...environment import Environment
     from ...dependencies import Dependency  # noqa: F401
+    from ...linkers import AppleDynamicLinker
 
 clang_color_args = {
     'auto': ['-Xclang', '-fcolor-diagnostics'],
@@ -42,6 +44,12 @@ clang_optimization_args = {
 }  # type: T.Dict[str, T.List[str]]
 
 class ClangCompiler(GnuLikeCompiler):
+
+    if T.TYPE_CHECKING:
+        linker = AppleDynamicLinker([], MachineChoice.HOST, '', [])
+
+        def get_pch_name(self, name: str) -> str: ...
+
     def __init__(self, defines: T.Optional[T.Dict[str, str]]):
         super().__init__()
         self.id = 'clang'
@@ -79,13 +87,14 @@ class ClangCompiler(GnuLikeCompiler):
         myargs = ['-Werror=unknown-warning-option', '-Werror=unused-command-line-argument']
         if mesonlib.version_compare(self.version, '>=3.6.0'):
             myargs.append('-Werror=ignored-optimization-argument')
-        return super().has_multi_arguments(
+        # Mypy doesn't understand co-coperative inheritance
+        return super().has_multi_arguments(  # type: ignore
             myargs + args,
             env)
 
     def has_function(self, funcname: str, prefix: str, env: 'Environment', *,
                      extra_args: T.Optional[T.List[str]] = None,
-                     dependencies: T.Optional[T.List['Dependency']] = None) -> bool:
+                     dependencies: T.Optional[T.List['Dependency']] = None) -> T.Tuple[bool, bool]:
         if extra_args is None:
             extra_args = []
         # Starting with XCode 8, we need to pass this to force linker
@@ -95,8 +104,10 @@ class ClangCompiler(GnuLikeCompiler):
         # TODO: this really should be communicated by the linker
         if isinstance(self.linker, AppleDynamicLinker) and mesonlib.version_compare(self.version, '>=8.0'):
             extra_args.append('-Wl,-no_weak_imports')
-        return super().has_function(funcname, prefix, env, extra_args=extra_args,
-                                    dependencies=dependencies)
+        # Mypy doesn't understand co-coperative inheritance
+        ret = super().has_function(funcname, prefix, env, extra_args=extra_args,  # type: ignore
+                                   dependencies=dependencies)
+        return T.cast(T.Tuple[bool, bool], ret)
 
     def openmp_flags(self) -> T.List[str]:
         if mesonlib.version_compare(self.version, '>=3.8.0'):
@@ -125,7 +136,7 @@ class ClangCompiler(GnuLikeCompiler):
             return ['-fuse-ld={}'.format(linker)]
         return super().use_linker_args(linker)
 
-    def get_has_func_attribute_extra_args(self, name):
+    def get_has_func_attribute_extra_args(self, name: str) -> T.List[str]:
         # Clang only warns about unknown or ignored attributes, so force an
         # error.
         return ['-Werror=attributes']
diff --git a/run_mypy.py b/run_mypy.py
index a502a1ee4..92570bcff 100755
--- a/run_mypy.py
+++ b/run_mypy.py
@@ -18,6 +18,7 @@ modules = [
   'mesonbuild/compilers/mixins/arm.py',
   'mesonbuild/compilers/mixins/c2000.py',
   'mesonbuild/compilers/mixins/ccrx.py',
+  'mesonbuild/compilers/mixins/clang.py',
   'mesonbuild/compilers/mixins/clike.py',
   'mesonbuild/compilers/mixins/gnu.py',
   # 'mesonbuild/compilers/mixins/intel.py',