feat(operators): support global binary operator overloads

Resolve exact operand types and preserve declared operator return types.
Reject implicit STRING to BOOLEAN conversion at typed expression boundaries.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/CodeGen/ControlFlowGen.cc b/lib/CodeGen/ControlFlowGen.cc
index 17f43f2..0cf0c34 100644
--- a/lib/CodeGen/ControlFlowGen.cc
+++ b/lib/CodeGen/ControlFlowGen.cc
@@ -204,6 +204,14 @@ void CodeGen::emitCaseStmt(CaseStmtAST *Stmt) {
                 return nullptr;
             }
             Value *LabelValue = emitExpr(Label);
+            auto Overload = resolveOperator(Op, SelectorType, LabelType);
+            if (Overload.Signature && !Overload.Ambiguous) {
+                const TypeInfo *Result = resolveType(Overload.Signature->ReturnTypeName);
+                if (!Result || Result->Kind != TypeKind::Boolean) {
+                    reportError("CASE comparison must return BOOLEAN");
+                    return nullptr;
+                }
+            }
             return emitBinaryOp(Op, Selected, SelectorType, LabelValue, LabelType, Branch.Line);
         };
         if (!Branch.Lower) {