Machine file pkg_config_path overrides environment

This is consistent with c_args in machine file overriding CFLAGS from
env. This also spotted an issue where in a native build this resulted
in pkg_config_path being /bar instead of /foo:
`-Dpkg_config_path=/foo -Dbuild.pkg_config_path=/bar`

Fixes: #7573

2 files changed, 8 insertions, 6 deletions

diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index 9ed939b..d5d90f9 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -735,7 +735,9 @@ class CoreData:
         for k, v in options.items():
             if k.startswith('build.'):
                 k = k.split('.', 1)[1]
-            res[k] = v
+                res.setdefault(k, v)
+            else:
+                res[k] = v
         return res
 
     def copy_build_options_from_regular_ones(self):
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index e63e9bf..e3ea956 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -629,12 +629,12 @@ class Environment:
         self.properties = properties.default_missing()
         self.cmakevars = cmakevars.default_missing()
 
-        # Environment options override those from cross/native files
-        self.set_options_from_env()
-
         # Command line options override those from cross/native files
         self.raw_options.update(options.cmd_line_options)
 
+        # Take default value from env if not set in cross/native files or command line.
+        self.set_default_options_from_env()
+
         # Warn if the user is using two different ways of setting build-type
         # options that override each other
         if 'buildtype' in self.raw_options and \
@@ -727,7 +727,7 @@ class Environment:
                 per_machine_options[build_optname] = value
         self.raw_options = per_machine_options
 
-    def set_options_from_env(self):
+    def set_default_options_from_env(self):
         for for_machine in MachineChoice:
             p_env_pair = get_env_var_pair(for_machine, self.is_cross_build(), 'PKG_CONFIG_PATH')
             if p_env_pair is not None:
@@ -746,7 +746,7 @@ class Environment:
                 # FIXME: We should remember if we took the value from env to warn
                 # if it changes on future invocations.
                 if self.first_invocation:
-                    self.raw_options[key] = p_list
+                    self.raw_options.setdefault(key, p_list)
 
     def create_new_coredata(self, options: 'argparse.Namespace') -> None:
         # WARNING: Don't use any values from coredata in __init__. It gets