compilers: Tell mypy that the compiler mixins are just that

We do this by making the mixins inherit the Compiler class only when
mypy is examining the code (using some clever inheritance shenanigans).
This caught a bunch of issues, and also lets us delete a ton of code.

1 files changed, 8 insertions, 1 deletions

diff --git a/mesonbuild/compilers/mixins/ccrx.py b/mesonbuild/compilers/mixins/ccrx.py
index 4ac815a..fb82797 100644
--- a/mesonbuild/compilers/mixins/ccrx.py
+++ b/mesonbuild/compilers/mixins/ccrx.py
@@ -21,6 +21,13 @@ from ...mesonlib import EnvironmentException
 
 if T.TYPE_CHECKING:
     from ...environment import Environment
+    from ...compilers.compilers import Compiler
+else:
+    # This is a bit clever, for mypy we pretend that these mixins descend from
+    # Compiler, so we get all of the methods and attributes defined for us, but
+    # for runtime we make them descend from object (which all classes normally
+    # do). This gives up DRYer type checking, with no runtime impact
+    Compiler = object
 
 ccrx_buildtype_args = {
     'plain': [],
@@ -46,7 +53,7 @@ ccrx_debug_args = {
 }  # type: T.Dict[bool, T.List[str]]
 
 
-class CcrxCompiler:
+class CcrxCompiler(Compiler):
 
     if T.TYPE_CHECKING:
         is_cross = True