From f3ecf978a07b02681a4d70a9d83991e6661bf753 Mon Sep 17 00:00:00 2001
From: Ellie Hermaszewska <ellieh@nvidia.com>
Date: Tue, 29 Aug 2023 20:58:44 +0800
Subject: Correct parsing spirv with no rhs operands (#3161)

* Correct parsing spirv with no rhs operands

* Guard against eof
---
 source/slang/slang-parser.cpp                      | 29 +++++++++++++++-------
 .../spirv-asm/typed-assignment-syntax.slang        |  3 +++
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index 57a21a90a..7e6d7d308 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -6411,8 +6411,27 @@ namespace Slang
         // At this point we can also parse bitwise or expressions
         //
         while(!(parser->LookAheadToken(TokenType::RBrace)
-            || parser->LookAheadToken(TokenType::Semicolon)))
+            || parser->LookAheadToken(TokenType::Semicolon)
+            || parser->LookAheadToken(TokenType::EndOfFile))
+            || resultTypeOperand
+            || resultOperand)
         {
+            // Insert the LHS result-type operand
+            if(ret.operands.getCount() == opInfo->resultTypeIndex && resultTypeOperand)
+            {
+                ret.operands.add(*resultTypeOperand);
+                resultTypeOperand.reset();
+                continue;
+            }
+
+            // Insert the LHS result operand
+            if(ret.operands.getCount() == opInfo->resultIdIndex && resultOperand)
+            {
+                ret.operands.add(*resultOperand);
+                resultOperand.reset();
+                continue;
+            }
+
             if(ret.operands.getCount() == opInfo->maxOperandCount)
             {
                 parser->diagnose(
@@ -6423,14 +6442,6 @@ namespace Slang
                 );
             }
 
-            // Insert the LHS result-type operand
-            if(ret.operands.getCount() == opInfo->resultTypeIndex && resultTypeOperand)
-                ret.operands.add(*resultTypeOperand);
-
-            // Insert the LHS result operand
-            if(ret.operands.getCount() == opInfo->resultIdIndex && resultOperand)
-                ret.operands.add(*resultOperand);
-
             if(auto operand = parseSPIRVAsmOperand(parser))
             {
                 while(AdvanceIf(parser, TokenType::OpBitOr))
diff --git a/tests/language-feature/spirv-asm/typed-assignment-syntax.slang b/tests/language-feature/spirv-asm/typed-assignment-syntax.slang
index 5e449686e..a20fb6e43 100644
--- a/tests/language-feature/spirv-asm/typed-assignment-syntax.slang
+++ b/tests/language-feature/spirv-asm/typed-assignment-syntax.slang
@@ -18,6 +18,9 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
     int n = outputBuffer[i];
     int r = spirv_asm
     {
+        // Check that this still works even with no operands on the RHS
+        %unused : $$uint = OpUndef;
+        // More normal usage
         %two   : $$int = OpConstant 2;
         result : $$int = OpIMul $n %two;
     };
-- 
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