rename cflags_mapping to CFLAGS_MAPPING

This is PEP8 convention for a const variable. Also, make the type
Mapping, which doesn't have mutation methods. This means mypy will warn
us if someone tries to change this.

mesonbuild/compilers/compilers.py

@@ -91,18 +91,22 @@ languages_using_cppflags = {'c', 'cpp', 'objc', 'objcpp'}  # type: T.Set[str]
 soregex = re.compile(r'.*\.so(\.[0-9]+)?(\.[0-9]+)?(\.[0-9]+)?$')
 
 # Environment variables that each lang uses.
-cflags_mapping = {'c': 'CFLAGS',
-                  'cpp': 'CXXFLAGS',
-                  'cuda': 'CUFLAGS',
-                  'objc': 'OBJCFLAGS',
-                  'objcpp': 'OBJCXXFLAGS',
-                  'fortran': 'FFLAGS',
-                  'd': 'DFLAGS',
-                  'vala': 'VALAFLAGS',
-                  'rust': 'RUSTFLAGS'}  # type: T.Dict[str, str]
-
-cexe_mapping = {'c': 'CC',
-                'cpp': 'CXX'}
+CFLAGS_MAPPING: T.Mapping[str, str] = {
+    'c': 'CFLAGS',
+    'cpp': 'CXXFLAGS',
+    'cuda': 'CUFLAGS',
+    'objc': 'OBJCFLAGS',
+    'objcpp': 'OBJCXXFLAGS',
+    'fortran': 'FFLAGS',
+    'd': 'DFLAGS',
+    'vala': 'VALAFLAGS',
+    'rust': 'RUSTFLAGS',
+}
+
+CEXE_MAPPING: T.Mapping = {
+    'c': 'CC',
+   'cpp': 'CXX',
+}
 
 # All these are only for C-linkable languages; see `clink_langs` above.
 
@@ -1207,13 +1211,13 @@ def get_args_from_envvars(lang: str,
     Returns a tuple of (compile_flags, link_flags) for the specified language
     from the inherited environment
     """
-    if lang not in cflags_mapping:
+    if lang not in CFLAGS_MAPPING:
         return [], []
 
     compile_flags = []  # type: T.List[str]
     link_flags = []     # type: T.List[str]
 
-    env_compile_flags = get_env_var(for_machine, is_cross, cflags_mapping[lang])
+    env_compile_flags = get_env_var(for_machine, is_cross, CFLAGS_MAPPING[lang])
     if env_compile_flags is not None:
         compile_flags += split_args(env_compile_flags)
 

mesonbuild/modules/unstable_external_project.py

@@ -23,7 +23,7 @@ from ..mesonlib import (MesonException, Popen_safe, MachineChoice,
 from ..interpreterbase import InterpreterObject, InterpreterException, FeatureNew
 from ..interpreterbase import stringArgs, permittedKwargs
 from ..interpreter import Interpreter, DependencyHolder, InstallDir
-from ..compilers.compilers import cflags_mapping, cexe_mapping
+from ..compilers.compilers import CFLAGS_MAPPING, CEXE_MAPPING
 from ..dependencies.base import InternalDependency, PkgConfigDependency
 from ..environment import Environment
 from ..mesonlib import OptionKey
@@ -110,11 +110,11 @@ class ExternalProject(InterpreterObject):
         link_args = []
         self.run_env = os.environ.copy()
         for lang, compiler in self.env.coredata.compilers[MachineChoice.HOST].items():
-            if any(lang not in i for i in (cexe_mapping, cflags_mapping)):
+            if any(lang not in i for i in (CEXE_MAPPING, CFLAGS_MAPPING)):
                 continue
             cargs = self.env.coredata.get_external_args(MachineChoice.HOST, lang)
-            self.run_env[cexe_mapping[lang]] = self._quote_and_join(compiler.get_exelist())
-            self.run_env[cflags_mapping[lang]] = self._quote_and_join(cargs)
+            self.run_env[CEXE_MAPPING[lang]] = self._quote_and_join(compiler.get_exelist())
+            self.run_env[CFLAGS_MAPPING[lang]] = self._quote_and_join(cargs)
             if not link_exelist:
                 link_exelist = compiler.get_linker_exelist()
                 link_args = self.env.coredata.get_external_link_args(MachineChoice.HOST, lang)

run_unittests.py

@@ -9347,7 +9347,7 @@ def unset_envs():
     # For unit tests we must fully control all command lines
     # so that there are no unexpected changes coming from the
     # environment, for example when doing a package build.
-    varnames = ['CPPFLAGS', 'LDFLAGS'] + list(mesonbuild.compilers.compilers.cflags_mapping.values())
+    varnames = ['CPPFLAGS', 'LDFLAGS'] + list(mesonbuild.compilers.compilers.CFLAGS_MAPPING.values())
     for v in varnames:
         if v in os.environ:
             del os.environ[v]