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.

mesonbuild/compilers/c.py

@@ -209,7 +209,9 @@ def get_std_shared_lib_link_args(self):
     def _get_search_dirs(self, env):
         extra_args = ['--print-search-dirs']
         stdo = None
-        with self._build_wrapper('', env, extra_args, None, 'compile', True) as p:
+        with self._build_wrapper('', env, extra_args=extra_args,
+                                 dependencies=None, mode='compile',
+                                 want_output=True) as p:
             stdo = p.stdo
         return stdo
 
@@ -361,13 +363,14 @@ def sanity_check(self, work_dir, environment):
         code = 'int main(int argc, char **argv) { int class=0; return class; }\n'
         return self.sanity_check_impl(work_dir, environment, 'sanitycheckc.c', code)
 
-    def check_header(self, hname, prefix, env, extra_args=None, dependencies=None):
+    def check_header(self, hname, prefix, env, *, extra_args=None, dependencies=None):
         fargs = {'prefix': prefix, 'header': hname}
         code = '''{prefix}
         #include <{header}>'''
-        return self.compiles(code.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(code.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
-    def has_header(self, hname, prefix, env, extra_args=None, dependencies=None):
+    def has_header(self, hname, prefix, env, *, extra_args=None, dependencies=None):
         fargs = {'prefix': prefix, 'header': hname}
         code = '''{prefix}
         #ifdef __has_include
@@ -377,10 +380,10 @@ def has_header(self, hname, prefix, env, extra_args=None, dependencies=None):
         #else
          #include <{header}>
         #endif'''
-        return self.compiles(code.format(**fargs), env, extra_args,
-                             dependencies, 'preprocess')
+        return self.compiles(code.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies, mode='preprocess')
 
-    def has_header_symbol(self, hname, symbol, prefix, env, extra_args=None, dependencies=None):
+    def has_header_symbol(self, hname, symbol, prefix, env, *, extra_args=None, dependencies=None):
         fargs = {'prefix': prefix, 'header': hname, 'symbol': symbol}
         t = '''{prefix}
         #include <{header}>
@@ -390,7 +393,8 @@ def has_header_symbol(self, hname, symbol, prefix, env, extra_args=None, depende
                 {symbol};
             #endif
         }}'''
-        return self.compiles(t.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
     def _get_compiler_check_args(self, env, extra_args, dependencies, mode='compile'):
         if callable(extra_args):
@@ -437,18 +441,19 @@ def _get_compiler_check_args(self, env, extra_args, dependencies, mode='compile'
         args += extra_args
         return args
 
-    def compiles(self, code, env, extra_args=None, dependencies=None, mode='compile'):
+    def compiles(self, code, env, *, extra_args=None, dependencies=None, mode='compile'):
         with self._build_wrapper(code, env, extra_args, dependencies, mode) as p:
             return p.returncode == 0
 
     def _build_wrapper(self, code, env, extra_args, dependencies=None, mode='compile', want_output=False):
         args = self._get_compiler_check_args(env, extra_args, dependencies, mode)
         return self.compile(code, args, mode, want_output=want_output)
 
-    def links(self, code, env, extra_args=None, dependencies=None):
-        return self.compiles(code, env, extra_args, dependencies, mode='link')
+    def links(self, code, env, *, extra_args=None, dependencies=None):
+        return self.compiles(code, env, extra_args=extra_args,
+                             dependencies=dependencies, mode='link')
 
-    def run(self, code, env, extra_args=None, dependencies=None):
+    def run(self, code, env, *, extra_args=None, dependencies=None):
         if self.is_cross and self.exe_wrapper is None:
             raise CrossNoRunException('Can not run test applications in this cross environment.')
         with self._build_wrapper(code, env, extra_args, dependencies, mode='link', want_output=True) as p:
@@ -478,7 +483,8 @@ def _compile_int(self, expression, prefix, env, extra_args, dependencies):
         t = '''#include <stdio.h>
         {prefix}
         int main() {{ static int a[1-2*!({expression})]; a[0]=0; return 0; }}'''
-        return self.compiles(t.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
     def cross_compute_int(self, expression, low, high, guess, prefix, env, extra_args, dependencies):
         # Try user's guess first
@@ -528,7 +534,7 @@ def cross_compute_int(self, expression, low, high, guess, prefix, env, extra_arg
 
         return low
 
-    def compute_int(self, expression, low, high, guess, prefix, env, extra_args=None, dependencies=None):
+    def compute_int(self, expression, low, high, guess, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         if self.is_cross:
@@ -540,14 +546,15 @@ def compute_int(self, expression, low, high, guess, prefix, env, extra_args=None
             printf("%ld\\n", (long)({expression}));
             return 0;
         }};'''
-        res = self.run(t.format(**fargs), env, extra_args, dependencies)
+        res = self.run(t.format(**fargs), env, extra_args=extra_args,
+                       dependencies=dependencies)
         if not res.compiled:
             return -1
         if res.returncode != 0:
             raise EnvironmentException('Could not run compute_int test binary.')
         return int(res.stdout)
 
-    def cross_sizeof(self, typename, prefix, env, extra_args=None, dependencies=None):
+    def cross_sizeof(self, typename, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         fargs = {'prefix': prefix, 'type': typename}
@@ -556,30 +563,33 @@ def cross_sizeof(self, typename, prefix, env, extra_args=None, dependencies=None
         int main(int argc, char **argv) {{
             {type} something;
         }}'''
-        if not self.compiles(t.format(**fargs), env, extra_args, dependencies):
+        if not self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies):
             return -1
         return self.cross_compute_int('sizeof(%s)' % typename, None, None, None, prefix, env, extra_args, dependencies)
 
-    def sizeof(self, typename, prefix, env, extra_args=None, dependencies=None):
+    def sizeof(self, typename, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         fargs = {'prefix': prefix, 'type': typename}
         if self.is_cross:
-            return self.cross_sizeof(typename, prefix, env, extra_args, dependencies)
+            return self.cross_sizeof(typename, prefix, env, extra_args=extra_args,
+                                     dependencies=dependencies)
         t = '''#include<stdio.h>
         {prefix}
         int main(int argc, char **argv) {{
             printf("%ld\\n", (long)(sizeof({type})));
             return 0;
         }};'''
-        res = self.run(t.format(**fargs), env, extra_args, dependencies)
+        res = self.run(t.format(**fargs), env, extra_args=extra_args,
+                       dependencies=dependencies)
         if not res.compiled:
             return -1
         if res.returncode != 0:
             raise EnvironmentException('Could not run sizeof test binary.')
         return int(res.stdout)
 
-    def cross_alignment(self, typename, prefix, env, extra_args=None, dependencies=None):
+    def cross_alignment(self, typename, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         fargs = {'prefix': prefix, 'type': typename}
@@ -588,7 +598,8 @@ def cross_alignment(self, typename, prefix, env, extra_args=None, dependencies=N
         int main(int argc, char **argv) {{
             {type} something;
         }}'''
-        if not self.compiles(t.format(**fargs), env, extra_args, dependencies):
+        if not self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies):
             return -1
         t = '''#include <stddef.h>
         {prefix}
@@ -598,11 +609,12 @@ def cross_alignment(self, typename, prefix, env, extra_args=None, dependencies=N
         }};'''
         return self.cross_compute_int('offsetof(struct tmp, target)', None, None, None, t.format(**fargs), env, extra_args, dependencies)
 
-    def alignment(self, typename, prefix, env, extra_args=None, dependencies=None):
+    def alignment(self, typename, prefix, env, *, extra_args=None, dependencies=None):
         if extra_args is None:
             extra_args = []
         if self.is_cross:
-            return self.cross_alignment(typename, prefix, env, extra_args, dependencies)
+            return self.cross_alignment(typename, prefix, env, extra_args=extra_args,
+                                        dependencies=dependencies)
         fargs = {'prefix': prefix, 'type': typename}
         t = '''#include <stdio.h>
         #include <stddef.h>
@@ -615,7 +627,8 @@ def alignment(self, typename, prefix, env, extra_args=None, dependencies=None):
             printf("%d", (int)offsetof(struct tmp, target));
             return 0;
         }}'''
-        res = self.run(t.format(**fargs), env, extra_args, dependencies)
+        res = self.run(t.format(**fargs), env, extra_args=extra_args,
+                       dependencies=dependencies)
         if not res.compiled:
             raise EnvironmentException('Could not compile alignment test.')
         if res.returncode != 0:
@@ -659,7 +672,7 @@ def get_return_value(self, fname, rtype, prefix, env, extra_args, dependencies):
         int main(int argc, char *argv[]) {{
             printf ("{fmt}", {cast} {f}());
         }}'''.format(**fargs)
-        res = self.run(code, env, extra_args, dependencies)
+        res = self.run(code, env, extra_args=extra_args, dependencies=dependencies)
         if not res.compiled:
             m = 'Could not get return value of {}()'
             raise EnvironmentException(m.format(fname))
@@ -728,7 +741,7 @@ def _have_prototype_templ():
         }}'''
         return head, main
 
-    def has_function(self, funcname, prefix, env, extra_args=None, dependencies=None):
+    def has_function(self, funcname, prefix, env, *, extra_args=None, dependencies=None):
         """
         First, this function looks for the symbol in the default libraries
         provided by the compiler (stdlib + a few others usually). If that
@@ -776,7 +789,8 @@ def has_function(self, funcname, prefix, env, extra_args=None, dependencies=None
             head, main = self._no_prototype_templ()
         templ = head + stubs_fail + main
 
-        if self.links(templ.format(**fargs), env, extra_args, dependencies):
+        if self.links(templ.format(**fargs), env, extra_args=extra_args,
+                      dependencies=dependencies):
             return True
 
         # MSVC does not have compiler __builtin_-s.
@@ -809,9 +823,10 @@ def has_function(self, funcname, prefix, env, extra_args=None, dependencies=None
             #endif
         #endif
         }}'''
-        return self.links(t.format(**fargs), env, extra_args, dependencies)
+        return self.links(t.format(**fargs), env, extra_args=extra_args,
+                          dependencies=dependencies)
 
-    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):
         if extra_args is None:
             extra_args = []
         fargs = {'prefix': prefix, 'type': typename, 'name': 'foo'}
@@ -825,15 +840,17 @@ def has_members(self, typename, membernames, prefix, env, extra_args=None, depen
             {type} {name};
             {members}
         }};'''
-        return self.compiles(t.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
     def has_type(self, typename, prefix, env, extra_args, dependencies=None):
         fargs = {'prefix': prefix, 'type': typename}
         t = '''{prefix}
         void bar() {{
             sizeof({type});
         }};'''
-        return self.compiles(t.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
     def symbols_have_underscore_prefix(self, env):
         '''
@@ -1221,11 +1238,13 @@ def get_options(self):
 
     # Elbrus C compiler does not have lchmod, but there is only linker warning, not compiler error.
     # So we should explicitly fail at this case.
-    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 funcname == 'lchmod':
             return False
         else:
-            return super().has_function(funcname, prefix, env, extra_args, dependencies)
+            return super().has_function(funcname, prefix, env,
+                                        extra_args=extra_args,
+                                        dependencies=dependencies)
 
 
 class IntelCCompiler(IntelCompiler, CCompiler):

mesonbuild/compilers/compilers.py

@@ -868,10 +868,10 @@ def get_define(self, dname, prefix, env, extra_args, dependencies):
     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 @@ def has_multi_arguments(self, args, env):
             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 @@ def has_function(self, funcname, prefix, env, extra_args=None, dependencies=None
         # 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'):

mesonbuild/compilers/cpp.py

@@ -62,9 +62,11 @@ def get_compiler_check_args(self):
         # too strict without this and always fails.
         return super().get_compiler_check_args() + ['-fpermissive']
 
-    def has_header_symbol(self, hname, symbol, prefix, env, extra_args=None, dependencies=None):
+    def has_header_symbol(self, hname, symbol, prefix, env, *, extra_args=None, dependencies=None):
         # Check if it's a C-like symbol
-        if super().has_header_symbol(hname, symbol, prefix, env, extra_args, dependencies):
+        if super().has_header_symbol(hname, symbol, prefix, env,
+                                     extra_args=extra_args,
+                                     dependencies=dependencies):
             return True
         # Check if it's a class or a template
         if extra_args is None:
@@ -74,7 +76,8 @@ def has_header_symbol(self, hname, symbol, prefix, env, extra_args=None, depende
         #include <{header}>
         using {symbol};
         int main () {{ return 0; }}'''
-        return self.compiles(t.format(**fargs), env, extra_args, dependencies)
+        return self.compiles(t.format(**fargs), env, extra_args=extra_args,
+                             dependencies=dependencies)
 
     def _test_cpp_std_arg(self, cpp_std_value):
         # Test whether the compiler understands a -std=XY argument
@@ -246,11 +249,13 @@ def get_options(self):
 
     # Elbrus C++ compiler does not have lchmod, but there is only linker warning, not compiler error.
     # So we should explicitly fail at this case.
-    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 funcname == 'lchmod':
             return False
         else:
-            return super().has_function(funcname, prefix, env, extra_args, dependencies)
+            return super().has_function(funcname, prefix, env,
+                                        extra_args=extra_args,
+                                        dependencies=dependencies)
 
 
 class IntelCPPCompiler(IntelCompiler, CPPCompiler):

mesonbuild/compilers/d.py

@@ -303,7 +303,7 @@ def _get_compiler_check_args(self, env, extra_args, dependencies, mode='compile'
         args += extra_args
         return args
 
-    def compiles(self, code, env, extra_args=None, dependencies=None, mode='compile'):
+    def compiles(self, code, env, *, extra_args=None, dependencies=None, mode='compile'):
         args = self._get_compiler_check_args(env, extra_args, dependencies, mode)
 
         with self.compile(code, args, mode) as p:

mesonbuild/compilers/fortran.py

@@ -210,16 +210,18 @@ def gen_import_library_args(self, implibname):
     def _get_compiler_check_args(self, env, extra_args, dependencies, mode='compile'):
         return CCompiler._get_compiler_check_args(self, env, extra_args, dependencies, mode='compile')
 
-    def compiles(self, code, env, extra_args=None, dependencies=None, mode='compile'):
-        return CCompiler.compiles(self, code, env, extra_args, dependencies, mode)
+    def compiles(self, code, env, *, extra_args=None, dependencies=None, mode='compile'):
+        return CCompiler.compiles(self, code, env, extra_args=extra_args,
+                                  dependencies=dependencies, mode=mode)
 
     def _build_wrapper(self, code, env, extra_args, dependencies=None, mode='compile', want_output=False):
         return CCompiler._build_wrapper(self, code, env, extra_args, dependencies, mode, want_output)
 
-    def links(self, code, env, extra_args=None, dependencies=None):
-        return CCompiler.links(self, code, env, extra_args, dependencies)
+    def links(self, code, env, *, extra_args=None, dependencies=None):
+        return CCompiler.links(self, code, env, extra_args=extra_args,
+                               dependencies=dependencies)
 
-    def run(self, code, env, extra_args=None, dependencies=None):
+    def run(self, code, env, *, extra_args=None, dependencies=None):
         return CCompiler.run(self, code, env, extra_args, dependencies)
 
     def _get_patterns(self, *args, **kwargs):