feat(codegen): accept pointer types to any C type in EXTERN

A pseudocode pointer type now counts as a C type, in EXTERN signatures
and as a C-struct field, when it finally points to a non-void C type or a
C struct, as in TYPE PInt = ^C_INT. A pointer cycle such as TYPE P = ^P
and a pointer to a pseudocode type stay rejected.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/include/cps/TypeSystem.h b/include/cps/TypeSystem.h
index 1c1e422..f8427f3 100644
--- a/include/cps/TypeSystem.h
+++ b/include/cps/TypeSystem.h
@@ -154,12 +154,15 @@ public:
                       std::string &Err);
     bool sameType(const std::string &Left, const std::string &Right) const;
     const TypeInfo *promoteCScalar(const TypeInfo *Info) const;
-    // A TYPE record (not a CLASS) whose fields are C scalars, C pointers,
-    // C structs or pointer types to C structs. Otherwise Why, if given,
-    // names the first offending field and its type.
+    // Follows pseudocode pointer types to the type they finally point to:
+    // Info itself when it is not one, nullptr for a cycle (TYPE P = ^P).
+    const TypeInfo *pointerBase(const TypeInfo *Info) const;
+    // A TYPE record (not a CLASS) whose fields are C types, C structs or
+    // pointer types to either. Otherwise Why, if given, names the first
+    // offending field and its type.
     bool isCStruct(const TypeInfo *Info, std::string *Why = nullptr) const;
     // Crosses the EXTERN "C" boundary: a non-void C type, a C struct or a
-    // pointer type to one.
+    // pointer type to either.
     bool isExternType(const TypeInfo *Info) const;
     const TypeInfo *commonCScalar(const TypeInfo *Left, const TypeInfo *Right) const;