Environment: Fix passing envrionment variables CPPFLAGS and CFLAGS

Or other language flags that use CPPFLAGS (like CXXFLAGS). The problem
here is actually rather simple, `dict.setdefault()` doesn't work like I
thought it did, I thought it created a weak entry, but it actually is
equivalent to:
```python
if k not in dict:
    dict[k] = v
```
Instead we'll use an intermediate dictionary (a default dictionary
actually, since that makes things a little cleaner) and then add the
keys from that dict to self.options as applicable.

Test case written by Jussi, Fix by Dylan

Co-authored-by: Jussi Pakkanen
Fixes: #8361
Fixes: #8345

1 files changed, 8 insertions, 0 deletions

diff --git a/run_unittests.py b/run_unittests.py
index 0bd6d4b..3aa1cb3 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -5476,6 +5476,14 @@ class AllPlatformTests(BasePlatformTests):
         projinfo = self.introspect('--projectinfo')
         self.assertEqual(projinfo['version'], '1.0.0')
 
+    def test_cflags_cppflags(self):
+        envs = {'CPPFLAGS': '-DCPPFLAG',
+                'CFLAGS': '-DCFLAG',
+                'CXXFLAGS': '-DCXXFLAG'}
+        srcdir = os.path.join(self.unit_test_dir, '90 multiple envvars')
+        self.init(srcdir, override_envvars=envs)
+        self.build()
+
 
 class FailureTests(BasePlatformTests):
     '''