compilers: Fix accidental coredata mutations

mesonbuild/compilers/fortran.py

@@ -68,7 +68,8 @@ class FortranCompiler(CLikeCompiler, Compiler):
 
         source_name.write_text('print *, "Fortran compilation is working."; end')
 
-        extra_flags = environment.coredata.get_external_args(self.for_machine, self.language)
+        extra_flags = []
+        extra_flags += environment.coredata.get_external_args(self.for_machine, self.language)
         extra_flags += environment.coredata.get_external_link_args(self.for_machine, self.language)
         extra_flags += self.get_always_args()
         # %% build the test executable "sanitycheckf"

mesonbuild/compilers/objc.py

@@ -44,7 +44,8 @@ class ObjCCompiler(CLikeCompiler, Compiler):
         # TODO try to use sanity_check_impl instead of duplicated code
         source_name = os.path.join(work_dir, 'sanitycheckobjc.m')
         binary_name = os.path.join(work_dir, 'sanitycheckobjc')
-        extra_flags = environment.coredata.get_external_args(self.for_machine, self.language)
+        extra_flags = []
+        extra_flags += environment.coredata.get_external_args(self.for_machine, self.language)
         if self.is_cross:
             extra_flags += self.get_compile_only_args()
         else:

mesonbuild/compilers/objcpp.py

@@ -43,7 +43,8 @@ class ObjCPPCompiler(CLikeCompiler, Compiler):
         # TODO try to use sanity_check_impl instead of duplicated code
         source_name = os.path.join(work_dir, 'sanitycheckobjcpp.mm')
         binary_name = os.path.join(work_dir, 'sanitycheckobjcpp')
-        extra_flags = environment.coredata.get_external_args(self.for_machine, self.language)
+        extra_flags = []
+        extra_flags += environment.coredata.get_external_args(self.for_machine, self.language)
         if self.is_cross:
             extra_flags += self.get_compile_only_args()
         else:

mesonbuild/compilers/swift.py

@@ -98,7 +98,8 @@ class SwiftCompiler(Compiler):
         src = 'swifttest.swift'
         source_name = os.path.join(work_dir, src)
         output_name = os.path.join(work_dir, 'swifttest')
-        extra_flags = environment.coredata.get_external_args(self.for_machine, self.language)
+        extra_flags = []
+        extra_flags += environment.coredata.get_external_args(self.for_machine, self.language)
         if self.is_cross:
             extra_flags += self.get_compile_only_args()
         else:

mesonbuild/compilers/vala.py

@@ -94,7 +94,8 @@ class ValaCompiler(Compiler):
 
     def sanity_check(self, work_dir, environment):
         code = 'class MesonSanityCheck : Object { }'
-        extra_flags = environment.coredata.get_external_args(self.for_machine, self.language)
+        extra_flags = []
+        extra_flags += environment.coredata.get_external_args(self.for_machine, self.language)
         if self.is_cross:
             extra_flags += self.get_compile_only_args()
         else:
@@ -117,7 +118,8 @@ class ValaCompiler(Compiler):
         # no extra dirs are specified.
         if not extra_dirs:
             code = 'class MesonFindLibrary : Object { }'
-            args = env.coredata.get_external_args(self.for_machine, self.language)
+            args = []
+            args += env.coredata.get_external_args(self.for_machine, self.language)
             vapi_args = ['--pkg', libname]
             args += vapi_args
             with self.cached_compile(code, env.coredata, extra_args=args, mode='compile') as p: