test(C0.1): pin named #import c block — name namespaces decls, #define/#flags reach the unit's compile

examples/1618-cimport-named-defines.sx

@@ -0,0 +1,18 @@
+// Pins the NAMED `#import c` block (PLAN-C C0.1): the block's name
+// namespaces the decls synthesized from `#include`, and `#define` /
+// `#flags` entries reach the unit's clang invocation — the macro decides
+// what cdef_value answers.
+#import "modules/std.sx";
+
+cu :: #import c {
+    #include "1618-cimport-named-defines/cdef.h";
+    #source  "1618-cimport-named-defines/cdef.c";
+    #define  "CDEF_BASE=42";
+    #flags   "-O2";
+};
+
+main :: () -> i32 {
+    print("value = {}\n", cu.cdef_value());
+    print("doubled = {}\n", cu.cdef_doubled(21));
+    0
+}

examples/1618-cimport-named-defines/cdef.c

@@ -0,0 +1,6 @@
+#include "cdef.h"
+#ifndef CDEF_BASE
+#define CDEF_BASE 1
+#endif
+int cdef_value(void) { return CDEF_BASE; }
+int cdef_doubled(int x) { return x * 2; }

examples/1618-cimport-named-defines/cdef.h

@@ -0,0 +1,5 @@
+#ifndef CDEF_H
+#define CDEF_H
+int cdef_value(void);
+int cdef_doubled(int x);
+#endif

examples/expected/1618-cimport-named-defines.exit

@@ -0,0 +1 @@
+0

examples/expected/1618-cimport-named-defines.stderr

@@ -0,0 +1 @@
+

examples/expected/1618-cimport-named-defines.stdout

@@ -0,0 +1,2 @@
+value = 42
+doubled = 42