compilers: make sanity_check_impl a protected method

It's an implementation detail after all

mesonbuild/compilers/c.py

@@ -64,7 +64,7 @@ class CCompiler(CLikeCompiler, Compiler):
 
     def sanity_check(self, work_dir, environment):
         code = 'int main(void) { int class=0; return class; }\n'
-        return self.sanity_check_impl(work_dir, environment, 'sanitycheckc.c', code)
+        return self._sanity_check_impl(work_dir, environment, 'sanitycheckc.c', code)
 
     def has_header_symbol(self, hname, symbol, prefix, env, *, extra_args=None, dependencies=None):
         fargs = {'prefix': prefix, 'header': hname, 'symbol': symbol}

mesonbuild/compilers/cpp.py

@@ -77,7 +77,7 @@ class CPPCompiler(CLikeCompiler, Compiler):
 
     def sanity_check(self, work_dir, environment):
         code = 'class breakCCompiler;int main(void) { return 0; }\n'
-        return self.sanity_check_impl(work_dir, environment, 'sanitycheckcpp.cc', code)
+        return self._sanity_check_impl(work_dir, environment, 'sanitycheckcpp.cc', code)
 
     def get_compiler_check_args(self):
         # -fpermissive allows non-conforming code to compile which is necessary

mesonbuild/compilers/mixins/clike.py

@@ -325,7 +325,7 @@ class CLikeCompiler:
     def gen_import_library_args(self, implibname: str) -> T.List[str]:
         return self.linker.import_library_args(implibname)
 
-    def sanity_check_impl(self, work_dir: str, environment: 'Environment',
+    def _sanity_check_impl(self, work_dir: str, environment: 'Environment',
                          sname: str, code: str) -> None:
         mlog.debug('Sanity testing ' + self.get_display_language() + ' compiler:', ' '.join(self.exelist))
         mlog.debug('Is cross compiler: %s.' % str(self.is_cross))
@@ -383,7 +383,7 @@ class CLikeCompiler:
 
     def sanity_check(self, work_dir: str, environment: 'Environment') -> None:
         code = 'int main(void) { int class=0; return class; }\n'
-        return self.sanity_check_impl(work_dir, environment, 'sanitycheckc.c', code)
+        return self._sanity_check_impl(work_dir, environment, 'sanitycheckc.c', code)
 
     def check_header(self, hname: str, prefix: str, env: 'Environment', *,
                      extra_args: T.Optional[T.List[str]] = None,