compilers: Use keyword only arguments for compiler interfaces

Because we need to inherit them in some cases, and python's
keyword-or-positional arguments make this really painful, especially
with inheritance. They do this in two ways:

1) If you want to intercept the arguments you need to check for both a
   keyword and a positional argument, because you could get either. Then
   you need to make sure that you only pass one of those down to the
   next layer.

2) After you do that, if the layer below you decides to do the same
   thing, but uses the other form (you used keyword by the lower level
   uses positional or vice versa), then you'll get a TypeError since two
   layers down got the argument as both a positional and a keyword.

All of this is bad. Fortunately python 3.x provides a mechanism to solve
this, keyword only arguments. These arguments cannot be based
positionally, the interpreter will give us an error in that case.

I have made a best effort to do this correctly, and I've verified it
with GCC, Clang, ICC, and MSVC, but there are other compilers like Arm
and Elbrus that I don't have access to.

1 files changed, 5 insertions, 4 deletions

diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index 495663e..85a8480 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -868,10 +868,10 @@ class Compiler:
     def compute_int(self, expression, low, high, guess, prefix, env, extra_args, dependencies):
         raise EnvironmentException('%s does not support compute_int ' % self.get_id())
 
-    def has_members(self, typename, membernames, prefix, env, extra_args=None, dependencies=None):
+    def has_members(self, typename, membernames, prefix, env, *, extra_args=None, dependencies=None):
         raise EnvironmentException('%s does not support has_member(s) ' % self.get_id())
 
-    def has_type(self, typename, prefix, env, extra_args, dependencies=None):
+    def has_type(self, typename, prefix, env, extra_args, *, dependencies=None):
         raise EnvironmentException('%s does not support has_type ' % self.get_id())
 
     def symbols_have_underscore_prefix(self, env):
@@ -1614,7 +1614,7 @@ class ClangCompiler(GnuLikeCompiler):
             myargs + args,
             env)
 
-    def has_function(self, funcname, prefix, env, extra_args=None, dependencies=None):
+    def has_function(self, funcname, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         # Starting with XCode 8, we need to pass this to force linker
@@ -1623,7 +1623,8 @@ class ClangCompiler(GnuLikeCompiler):
         # https://github.com/Homebrew/homebrew-core/issues/3727
         if self.compiler_type.is_osx_compiler and version_compare(self.version, '>=8.0'):
             extra_args.append('-Wl,-no_weak_imports')
-        return super().has_function(funcname, prefix, env, extra_args, dependencies)
+        return super().has_function(funcname, prefix, env, extra_args=extra_args,
+                                    dependencies=dependencies)
 
     def openmp_flags(self):
         if version_compare(self.version, '>=3.8.0'):