feat: records with designator lvalues, and pointer types (CIE 4.1/4.2)

- New CodeGen::emitLValue resolves any designator — variable, checked
  array element, record field chain (CreateStructGEP via the record
  payload), pointer deref (with the null-pointer [Fatal] check) — to an
  address + type name; loadFromLValue centralizes the rvalue read and the
  STRING null->"" guard, so zero-initialized STRING fields read as "".
- Designator assignment stores through emitLValue + emitCoercedExpr;
  whole-record copies (r2 <- r1, array elements, BYVAL args, RETURN) are
  aggregate loads/stores with name-checked admission.
- getExprTypeInfo walks designator chains statically (field types from
  the record payload, deref to the pointee), so records/pointers type
  correctly in every expression context.
- Address-of ^x admits into a pointer target only when the designator's
  type name equals the declared pointee exactly (nominal, strict: the
  guide's own ^INTEGER-at-a-Season example is a compile error by design);
  ^arr[i] and ^rec.field work through the same lvalue path.
- Verified: the guide's §4.2 StudentRecord example (minus DATE), nested
  records, arrays of records with Form[i].YearGroup writes, record
  BYREF/BYVAL params, NodePtr = ^Node forward reference with writes
  through n1.Next^.Data, unset-pointer deref dying with [Fatal].

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/cps/CodeGen.h b/include/cps/CodeGen.h
index 713d02b..c0cbeb5 100644
--- a/include/cps/CodeGen.h
+++ b/include/cps/CodeGen.h
@@ -68,6 +68,17 @@ class CodeGen {
     // TYPE-system helpers (Designator.cc).
     void runTypePrePass(const std::vector<std::unique_ptr<StmtAST>> &Statements);
     llvm::Value *emitUserKindBinaryOp(BinaryExprAST *Bin, const TypeInfo *LT, const TypeInfo *RT);
+
+    // An addressable location and the pseudocode type stored there.
+    struct LValueInfo {
+        llvm::Value *Addr = nullptr;
+        std::string TypeName;
+    };
+    // Resolves a variable / array element / field chain / deref to an address
+    // (emitting index and null-pointer checks along the way).
+    bool emitLValue(ExprAST *E, LValueInfo &Out);
+    // The rvalue read: load + the STRING null->"" guard.
+    llvm::Value *loadFromLValue(const LValueInfo &LV);
     bool marshalCallArgs(const std::string &Callee,
                          const std::vector<std::unique_ptr<ExprAST>> &ArgExprs,
                          std::vector<llvm::Value*> &Out);