Fix micro expansion issue for __LINE__. (#3942)

source/slang/slang-preprocessor.cpp

@@ -857,6 +857,11 @@ struct ExpansionInputStream : InputStream
 
     TokenType peekRawTokenType() { return peekRawToken().type; }
 
+    void setInitiatingMacroSourceLoc(SourceLoc loc)
+    {
+        m_initiatingMacroInvocationLoc = loc;
+        m_isInExpansion = true;
+    }
 private:
         /// The base stream that macro expansion is being applied to
     InputStream*   m_base = nullptr;
@@ -868,6 +873,10 @@ struct ExpansionInputStream : InputStream
         /// nested macro invocations might be in flight.
     SourceLoc m_initiatingMacroInvocationLoc;
 
+        /// Whether this ExpansionStream is created in the middle of
+        /// another macro expansion.
+    bool m_isInExpansion = false;
+
         /// One token of lookahead
     Token m_lookaheadToken;
 
@@ -1429,7 +1438,7 @@ void ExpansionInputStream::_maybeBeginMacroInvocation()
         // invocation location for things like `__LINE__` uses inside
         // of macro bodies.
         //
-        if(activeStream == m_base)
+        if(!m_isInExpansion && activeStream == m_base)
         {
             m_initiatingMacroInvocationLoc = token.loc;
         }
@@ -2110,6 +2119,7 @@ void MacroInvocation::_initCurrentOpStream()
             // applies macro expansion to them.
             //
             ExpansionInputStream* expansion = new ExpansionInputStream(m_preprocessor, stream);
+            expansion->setInitiatingMacroSourceLoc(m_initiatingMacroInvocationLoc);
             m_currentOpStreams.push(expansion);
         }
         break;

tests/preprocessor/line-macro.slang

@@ -0,0 +1,14 @@
+//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK): -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer : register(u0);
+
+#define T(x) x
+#define LL T(__LINE__)
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    // CHECK: 13
+    outputBuffer[0] = LL;
+}