[PATCH] D100252: [clang] Fix for "Bug 27113 - MSVC-compat __identifier implementation incomplete"

[Melvin Fox via Phabricator via cfe-commits]

super_concat updated this revision to Diff 346595.
super_concat added a comment.

Correctly handle string literals and add more test cases. Also MSVC <https://godbolt.org/z/r1Eadzzzq> by default gives an error when trying to use `__identifier` with a string literal but disabling/surprising that error allows string literals to be used with `__identifier`. However given how esoteric it is, it wouldn't really be necessary for clang to give a warning or error like MSVC


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100252/new/

https://reviews.llvm.org/D100252

Files:
  clang/lib/Lex/PPMacroExpansion.cpp
  clang/test/Parser/MicrosoftExtensions.cpp


Index: clang/test/Parser/MicrosoftExtensions.cpp
===================================================================
--- clang/test/Parser/MicrosoftExtensions.cpp
+++ clang/test/Parser/MicrosoftExtensions.cpp
@@ -263,6 +263,12 @@
 
 extern int __identifier(and);
 
+int __identifier("baz") = 0;
+int bar = baz;
+
+void mangled_function();
+extern "C" void __identifier("?mangled_function@@YAXXZ")() {}
+
 void f() {
   __identifier(() // expected-error {{cannot convert '(' token to an identifier}}
   __identifier(void) // expected-error {{use of undeclared identifier 'void'}}
@@ -270,8 +276,10 @@
   // FIXME: We should pick a friendlier display name for this token kind.
   __identifier(1) // expected-error {{cannot convert <numeric_constant> token to an identifier}}
   __identifier(+) // expected-error {{cannot convert '+' token to an identifier}}
-  __identifier("foo") // expected-error {{cannot convert <string_literal> token to an identifier}}
   __identifier(;) // expected-error {{cannot convert ';' token to an identifier}}
+  __identifier("1"); // expected-error {{use of undeclared identifier '1'}}
+  __identifier("+"); // expected-error {{use of undeclared identifier '+'}}
+  __identifier(";"); // expected-error {{use of undeclared identifier ';'}}
 }
 
 class inline_definition_pure_spec {
Index: clang/lib/Lex/PPMacroExpansion.cpp
===================================================================
--- clang/lib/Lex/PPMacroExpansion.cpp
+++ clang/lib/Lex/PPMacroExpansion.cpp
@@ -25,6 +25,7 @@
 #include "clang/Lex/ExternalPreprocessorSource.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/LexDiagnostic.h"
+#include "clang/Lex/LiteralSupport.h"
 #include "clang/Lex/MacroArgs.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/Preprocessor.h"
@@ -1813,7 +1814,14 @@
 
     if (!Tok.isAnnotation() && Tok.getIdentifierInfo())
       Tok.setKind(tok::identifier);
-    else {
+    else if (Tok.is(tok::string_literal) && !Tok.hasUDSuffix()) {
+      StringLiteralParser Literal(Tok, *this);
+      if (Literal.hadError)
+        return;
+
+      Tok.setIdentifierInfo(getIdentifierInfo(Literal.GetString()));
+      Tok.setKind(tok::identifier);
+    } else {
       Diag(Tok.getLocation(), diag::err_pp_identifier_arg_not_identifier)
         << Tok.getKind();
       // Don't walk past anything that's not a real token.


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