fix: close type-safety holes found by adversarial review; update docs

Review findings (all reproduced, then fixed and re-verified):
- '^x' leaked as a raw address into any builtin context (s <- ^x printed
  the variable's bytes as a C string; NOT ^x, '&', and ^x = ^x compiled).
  Address-of is now rejected everywhere except a pointer-typed target.
- A whole-array variable passed the nominal gate as a value of its
  ELEMENT type (s <- arrayOfSeason stored the raw data pointer; = on it
  emitted invalid IR). Whole arrays are now rejected as operands and as
  coercion sources; array parameters are unaffected.
- Enum values smuggled into INTEGER through array subscripts and DECLARE
  bounds (a[Autumn], ARRAY[Spring:Winter]); both now go through
  emitCoercedExpr like every other INTEGER context.
- An array DECLAREd inside an IF/WHILE/REPEAT/FOR body and used after the
  block was a wild-pointer write (constant bounds) or a verifier dump
  (runtime bounds). Arrays are now block-scoped: control-flow bodies
  snapshot and restore the ArrayTable, so escape is a clean compile error.
- Duplicate parameter names silently shadowed (BYREF write-back defeated);
  now a parse error. Trailing comma in parameter lists accepted; now a
  parse error consistent with every other list.
- A variable/array/parameter/function could reuse a TYPE name; reserved.
- RETURN with a value inside a PROCEDURE was silently discarded (control
  did not return); now an error, as is a bare RETURN in a FUNCTION.
- INPUT r.f mis-parsed into a three-error cascade; now one clear error.
- Assigning to an enum constant now says so instead of 'Unknown variable'.

Docs: ARCH/CONVENTIONS/EXTENDING/SUBSYSTEMS/PITFALLS rewritten for the
TYPE system (ABI additions, nominal-typing invariants, admission-gate
doors, array-parameter ABI, new recipes, new sharp edges); README
features/TODO updated — random files are unblocked.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/CodeGen/Designator.cc b/lib/CodeGen/Designator.cc
index a0ffe28..ad0cc49 100644
--- a/lib/CodeGen/Designator.cc
+++ b/lib/CodeGen/Designator.cc
@@ -200,6 +200,15 @@ Value *CodeGen::loadFromLValue(const LValueInfo &LV) {
 Value *CodeGen::emitCoercedExpr(ExprAST *E, const TypeInfo *Target) {
     if (!E || !Target) return nullptr;
 
+    // A whole-array reference evaluates to its raw data pointer, and
+    // getExprTypeInfo reports the ELEMENT type for it — both would slip
+    // through the name check and smash the pointer into the target.
+    if (isWholeArrayVar(E)) {
+        reportError("A whole array cannot be used as a value of type %s; index it",
+                    Target->Name.c_str());
+        return nullptr;
+    }
+
     const TypeInfo *Src = getExprTypeInfo(E);
 
     if (Target->isUserKind()) {
@@ -239,6 +248,14 @@ Value *CodeGen::emitCoercedExpr(ExprAST *E, const TypeInfo *Target) {
         return emitExpr(E); // same nominal type: no conversion needed
     }
 
+    // ^x is a raw address: admissible ONLY where a pointer type is expected.
+    // Without this check the ptr would coerce into STRING/BOOLEAN silently.
+    if (dynamic_cast<AddrOfExprAST*>(E)) {
+        reportError("'^' (address-of) can only be used where a pointer type is expected (got %s)",
+                    Target->Name.c_str());
+        return nullptr;
+    }
+
     if (Src && Src->isUserKind()) {
         reportError("Cannot use a value of type %s where %s is expected",
                     Src->Name.c_str(), Target->Name.c_str());