Fix whitespace before token-paste of an argument.

The whitespace should come from the argument name in the macro
expansion, rather than from the token passed to the macro (same as it
does when not pasting).

Added a new test case for the change in behavior to stringize_space.c.

FileCheck'ized macro_paste_commaext.c, tweaked the test case, and
added a comment; no behavioral change to this test.

Differential Revision: https://reviews.llvm.org/D30427

llvm-svn: 302195

clang/lib/Lex/TokenLexer.cpp

@@ -183,6 +183,12 @@ void TokenLexer::ExpandFunctionArguments() {
     // preprocessor already verified that the following token is a macro name
     // when the #define was parsed.
     const Token &CurTok = Tokens[i];
+    // We don't want a space for the next token after a paste
+    // operator.  In valid code, the token will get smooshed onto the
+    // preceding one anyway. In assembler-with-cpp mode, invalid
+    // pastes are allowed through: in this case, we do not want the
+    // extra whitespace to be added.  For example, we want ". ## foo"
+    // -> ".foo" not ". foo".
     if (i != 0 && !Tokens[i-1].is(tok::hashhash) && CurTok.hasLeadingSpace())
       NextTokGetsSpace = true;
 
@@ -317,6 +323,7 @@ void TokenLexer::ExpandFunctionArguments() {
     const Token *ArgToks = ActualArgs->getUnexpArgument(ArgNo);
     unsigned NumToks = MacroArgs::getArgLength(ArgToks);
     if (NumToks) {  // Not an empty argument?
+      bool VaArgsPseudoPaste = false;
       // If this is the GNU ", ## __VA_ARGS__" extension, and we just learned
       // that __VA_ARGS__ expands to multiple tokens, avoid a pasting error when
       // the expander trys to paste ',' with the first token of the __VA_ARGS__
@@ -325,6 +332,7 @@ void TokenLexer::ExpandFunctionArguments() {
           ResultToks[ResultToks.size()-2].is(tok::comma) &&
           (unsigned)ArgNo == Macro->getNumArgs()-1 &&
           Macro->isVariadic()) {
+        VaArgsPseudoPaste = true;
         // Remove the paste operator, report use of the extension.
         PP.Diag(ResultToks.pop_back_val().getLocation(), diag::ext_paste_comma);
       }
@@ -344,18 +352,16 @@ void TokenLexer::ExpandFunctionArguments() {
                                    ResultToks.end()-NumToks, ResultToks.end());
       }
 
-      // If this token (the macro argument) was supposed to get leading
-      // whitespace, transfer this information onto the first token of the
-      // expansion.
-      //
-      // Do not do this if the paste operator occurs before the macro argument,
-      // as in "A ## MACROARG".  In valid code, the first token will get
-      // smooshed onto the preceding one anyway (forming AMACROARG).  In
-      // assembler-with-cpp mode, invalid pastes are allowed through: in this
-      // case, we do not want the extra whitespace to be added.  For example,
-      // we want ". ## foo" -> ".foo" not ". foo".
-      if (NextTokGetsSpace)
-        ResultToks[ResultToks.size()-NumToks].setFlag(Token::LeadingSpace);
+      // Transfer the leading whitespace information from the token
+      // (the macro argument) onto the first token of the
+      // expansion. Note that we don't do this for the GNU
+      // pseudo-paste extension ", ## __VA_ARGS__".
+      if (!VaArgsPseudoPaste) {
+        ResultToks[ResultToks.size() - NumToks].setFlagValue(Token::StartOfLine,
+                                                             false);
+        ResultToks[ResultToks.size() - NumToks].setFlagValue(
+            Token::LeadingSpace, NextTokGetsSpace);
+      }
 
       NextTokGetsSpace = false;
       continue;

clang/test/Preprocessor/macro_paste_commaext.c

@@ -1,13 +1,20 @@
-// RUN: %clang_cc1 %s -E | grep 'V);'
-// RUN: %clang_cc1 %s -E | grep 'W, 1, 2);'
-// RUN: %clang_cc1 %s -E | grep 'X, 1, 2);'
-// RUN: %clang_cc1 %s -E | grep 'Y,);'
-// RUN: %clang_cc1 %s -E | grep 'Z,);'
+// RUN: %clang_cc1 %s -E | FileCheck --strict-whitespace --match-full-lines %s
+
+// In the following tests, note that the output is sensitive to the
+// whitespace *preceeding* the varargs argument, as well as to
+// interior whitespace. AFAIK, this is the only case where whitespace
+// preceeding an argument matters, and might be considered a bug in
+// GCC. Nevertheless, since this feature is a GCC extension in the
+// first place, we'll follow along.
 
 #define debug(format, ...) format, ## __VA_ARGS__)
+// CHECK:V);
 debug(V);
-debug(W, 1, 2);
+// CHECK:W,1, 2);
+debug(W,1, 2);
+// CHECK:X, 1, 2);
 debug(X, 1, 2 );
+// CHECK:Y,);
 debug(Y, );
+// CHECK:Z,);
 debug(Z,);
-

clang/test/Preprocessor/stringize_space.c

@@ -18,3 +18,14 @@ f(
     1)
 
 // CHECK: {{^}}"-1"
+
+#define paste(a,b) str(a<b##ld)
+paste(hello1, wor)
+paste(hello2,
+      wor)
+paste(hello3,
+wor)
+
+// CHECK: {{^}}"hello1<world"
+// CHECK: {{^}}"hello2<world"
+// CHECK: {{^}}"hello3<world"