Revise how hidden implicit casts are recognized.

The old approach used an `isRewriter` flag in the emit logic, but I kind of need that flag to go away.
Instead, I now how the semantic checking pass detect whether an implicitly-generated type cast is in rewriter code, and if so it uses the new `HiddenImplicitCastExpr` AST node.
The emit logic then looks for that specific node and eliminates it.

1 files changed, 13 insertions, 1 deletions

diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index f21f9480c..556f141c0 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -987,7 +987,19 @@ namespace Slang
             RefPtr<ExpressionType>			toType,
             RefPtr<ExpressionSyntaxNode>	fromExpr)
         {
-            auto castExpr = new ImplicitCastExpr();
+            // In "rewrite" mode, we will generate a different syntax node
+            // to indicate that this type-cast was implicitly generated
+            // by the compiler, and shouldn't appear in the output code.
+            RefPtr<TypeCastExpressionSyntaxNode> castExpr;
+            if (isRewriteMode())
+            {
+                castExpr = new HiddenImplicitCastExpr();
+            }
+            else
+            {
+                castExpr = new ImplicitCastExpr();
+            }
+
             castExpr->Position = fromExpr->Position;
             castExpr->TargetType.type = toType;
             castExpr->Type = QualType(toType);