[PATCH] D142604: [Clang] Fix __VA_OPT__ implementation so that it treats the concatenation of a non-placemaker token and placemaker token as a non-placemaker token

[Shafik Yaghmour via Phabricator via cfe-commits]

shafik created this revision.
shafik added reviewers: aaron.ballman, erichkeane, hubert.reinterpretcast.
Herald added a project: All.
shafik requested review of this revision.

Currently the implementation of `__VA_OPT__` will treat the concatenation of a non-placemaker token and placemaker token as a placemaker token which is not correct. This will fix the implementation and treat the result as a non-placemaker token.

This fixes: https://github.com/llvm/llvm-project/issues/60268


https://reviews.llvm.org/D142604

Files:
  clang/lib/Lex/TokenLexer.cpp
  clang/test/Preprocessor/macro_vaopt_p1042r1.cpp


Index: clang/test/Preprocessor/macro_vaopt_p1042r1.cpp
===================================================================
--- clang/test/Preprocessor/macro_vaopt_p1042r1.cpp
+++ clang/test/Preprocessor/macro_vaopt_p1042r1.cpp
@@ -28,3 +28,9 @@
 #define H5C(X) H5B(X)
 5: H5C(H5A())
 // CHECK: 5: ab
+
+namespace GH60268 {
+#define H6(X, ...) __VA_OPT__(a ## X) ## b
+6: H6(, 1);  
+// CHECK: 6: ab
+}
Index: clang/lib/Lex/TokenLexer.cpp
===================================================================
--- clang/lib/Lex/TokenLexer.cpp
+++ clang/lib/Lex/TokenLexer.cpp
@@ -501,7 +501,7 @@
           assert(VCtx.isInVAOpt() && "should only happen inside a __VA_OPT__");
           VCtx.hasPlaceholderAfterHashhashAtStart();
         }
-        if (RParenAfter)
+        else if (RParenAfter)
           VCtx.hasPlaceholderBeforeRParen();
       }
       continue;
@@ -567,7 +567,7 @@
       continue;
     }
 
-    if (RParenAfter)
+    if (RParenAfter && !NonEmptyPasteBefore)
       VCtx.hasPlaceholderBeforeRParen();
 
     // If this is on the RHS of a paste operator, we've already copied the


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