From d58e08f8237a1888ceaad53402d534679ea83b1a Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Fri, 18 Nov 2022 12:37:27 -0800
Subject: Data flow validation pass for diagnosing derivative loss. (#2523)

---
 source/slang/slang-parser.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'source/slang/slang-parser.cpp')

diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index 7cd0cdce9..b513217c8 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -5086,6 +5086,14 @@ namespace Slang
         return tryExpr;
     }
 
+    static NodeBase* parseTreatAsDifferentiableExpr(Parser* parser, void* /*userData*/)
+    {
+        auto noDiffExpr = parser->astBuilder->create<TreatAsDifferentiableExpr>();
+        noDiffExpr->innerExpr = parser->ParseLeafExpression();
+        noDiffExpr->scope = parser->currentScope;
+        return noDiffExpr;
+    }
+
     static bool _isFinite(double value)
     {
         // Lets type pun double to uint64_t, so we can detect special double values
@@ -6670,6 +6678,7 @@ namespace Slang
         _makeParseExpr("nullptr", parseNullPtrExpr),
         _makeParseExpr("none", parseNoneExpr),
         _makeParseExpr("try",     parseTryExpr),
+        _makeParseExpr("no_diff", parseTreatAsDifferentiableExpr),
         _makeParseExpr("__TaggedUnion", parseTaggedUnionType),
         _makeParseExpr("__fwd_diff", parseForwardDifferentiate),
         _makeParseExpr("__bwd_diff", parseBackwardDifferentiate)
-- 
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