Clean up type checking of higher order expressions. (#2519)

* Clean up type checking of higher order expressions.

* Replace `goto` with `break` to pacify clang.

* Fix.

* Fixes.

* Fix more tests.

* Fix lowerWitnessTable parameter error.

* Exclude attributes from ast printing.

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/source/slang/slang-ast-support-types.cpp b/source/slang/slang-ast-support-types.cpp
index 1f30e0238..b550eaa68 100644
--- a/source/slang/slang-ast-support-types.cpp
+++ b/source/slang/slang-ast-support-types.cpp
@@ -1,6 +1,7 @@
 #include "slang-ast-support-types.h"
 #include "slang-ast-base.h"
 #include "slang-ast-type.h"
+#include "slang-ast-expr.h"
 
 namespace Slang
 {
@@ -34,4 +35,31 @@ void removeModifier(ModifiableSyntaxNode* syntax, Modifier* toRemove)
         prev = modifier;
     }
 }
+
+Expr* getInnerMostExprFromHigherOrderExpr(Expr* expr)
+{
+    HashSet<Expr*> workListSet;
+    while (auto higherOrder = as<HigherOrderInvokeExpr>(expr))
+    {
+        if (workListSet.Add(higherOrder))
+        {
+            expr = higherOrder->baseFunction;
+        }
+        else
+        {
+            // Circularity, return null.
+            return nullptr;
+        }
+    }
+    return expr;
+}
+
+UnownedStringSlice getHigherOrderOperatorName(HigherOrderInvokeExpr* expr)
+{
+    if (as<ForwardDifferentiateExpr>(expr))
+        return UnownedStringSlice("fwd_diff");
+    else if (as<BackwardDifferentiateExpr>(expr))
+        return UnownedStringSlice("bwd_diff");
+    return UnownedStringSlice();
+}
 }