environment, env2mfile: Don't shell split paths if they point to a valid executable

Fixes #11128

mesonbuild/environment.py

@@ -747,7 +747,10 @@ class Environment:
         for (name, evar), for_machine in itertools.product(opts, MachineChoice):
             p_env = _get_env_var(for_machine, self.is_cross_build(), evar)
             if p_env is not None:
-                self.binaries[for_machine].binaries.setdefault(name, mesonlib.split_args(p_env))
+                if os.path.exists(p_env):
+                    self.binaries[for_machine].binaries.setdefault(name, [p_env])
+                else:
+                    self.binaries[for_machine].binaries.setdefault(name, mesonlib.split_args(p_env))
 
     def _set_default_properties_from_env(self) -> None:
         """Properties which can also be set from the environment."""

mesonbuild/scripts/env2mfile.py

@@ -296,7 +296,10 @@ def detect_compilers_from_envvars(envvar_suffix: str = '') -> MachineInfo:
         compilerstr = os.environ.get(envvarname + envvar_suffix)
         if not compilerstr:
             continue
-        compiler = shlex.split(compilerstr)
+        if os.path.exists(compilerstr):
+            compiler = [compilerstr]
+        else:
+            compiler = shlex.split(compilerstr)
         infos.compilers[langname] = compiler
         lang_compile_args, lang_link_args = detect_language_args_from_envvars(langname, envvar_suffix)
         if lang_compile_args: