diff options
| -rw-r--r-- | clang/include/clang/Lex/Preprocessor.h | 1 | ||||
| -rw-r--r-- | clang/include/clang/Lex/VariadicMacroSupport.h | 56 | ||||
| -rw-r--r-- | clang/lib/Lex/PPDirectives.cpp | 25 |
3 files changed, 69 insertions, 13 deletions
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h index a058fbfbb4c..49a95986fd6 100644 --- a/clang/include/clang/Lex/Preprocessor.h +++ b/clang/include/clang/Lex/Preprocessor.h @@ -96,6 +96,7 @@ enum MacroUse { /// know anything about preprocessor-level issues like the \#include stack, /// token expansion, etc. class Preprocessor { + friend class VariadicMacroScopeGuard; std::shared_ptr<PreprocessorOptions> PPOpts; DiagnosticsEngine *Diags; LangOptions &LangOpts; diff --git a/clang/include/clang/Lex/VariadicMacroSupport.h b/clang/include/clang/Lex/VariadicMacroSupport.h new file mode 100644 index 00000000000..dd36e39f4e6 --- /dev/null +++ b/clang/include/clang/Lex/VariadicMacroSupport.h @@ -0,0 +1,56 @@ +//===- VariadicMacroSupport.h - scope-guards etc. -*- C++ -*---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines support types to help with preprocessing variadic macro
+// (i.e. macros that use: ellipses __VA_ARGS__ ) definitions and
+// expansions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H
+#define LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H
+
+#include "clang/Lex/Preprocessor.h"
+
+namespace clang {
+
+/// An RAII class that tracks when the Preprocessor starts and stops lexing the
+/// definition of a (ISO C/C++) variadic macro. As an example, this is useful
+/// for unpoisoning and repoisoning certain identifiers (such as __VA_ARGS__)
+/// that are only allowed in this context. Also, being a friend of the
+/// Preprocessor class allows it to access PP's cached identifiers directly (as
+/// opposed to performing a lookup each time).
+class VariadicMacroScopeGuard {
+ const Preprocessor &PP;
+ IdentifierInfo &Ident__VA_ARGS__;
+
+public:
+ VariadicMacroScopeGuard(const Preprocessor &P)
+ : PP(P), Ident__VA_ARGS__(*PP.Ident__VA_ARGS__) {
+ assert(Ident__VA_ARGS__.isPoisoned() && "__VA_ARGS__ should be poisoned "
+ "outside an ISO C/C++ variadic "
+ "macro definition!");
+ }
+
+ /// Client code should call this function just before the Preprocessor is
+ /// about to Lex tokens from the definition of a variadic (ISO C/C++) macro.
+ void enterScope() { Ident__VA_ARGS__.setIsPoisoned(false); }
+
+ /// Client code should call this function as soon as the Preprocessor has
+ /// either completed lexing the macro's definition tokens, or an error occured
+ /// and the context is being exited. This function is idempotent (might be
+ /// explicitly called, and then reinvoked via the destructor).
+ void exitScope() { Ident__VA_ARGS__.setIsPoisoned(true); }
+
+ ~VariadicMacroScopeGuard() { exitScope(); }
+};
+
+} // end namespace clang
+
+#endif
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp index b2450f516ba..6b09398e468 100644 --- a/clang/lib/Lex/PPDirectives.cpp +++ b/clang/lib/Lex/PPDirectives.cpp @@ -33,6 +33,7 @@ #include "clang/Lex/PreprocessorOptions.h" #include "clang/Lex/PTHLexer.h" #include "clang/Lex/Token.h" +#include "clang/Lex/VariadicMacroSupport.h" #include "llvm/ADT/ArrayRef.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/SmallVector.h" @@ -2290,6 +2291,10 @@ MacroInfo *Preprocessor::ReadOptionalMacroParameterListAndBody( Token Tok; LexUnexpandedToken(Tok); + // Used to un-poison and then re-poison identifiers of the __VA_ARGS__ ilk + // within their appropriate context. + VariadicMacroScopeGuard VariadicMacroScopeGuard(*this); + // If this is a function-like macro definition, parse the argument list, // marking each of the identifiers as being used as macro arguments. Also, // check other constraints on the first token of the macro body. @@ -2314,14 +2319,14 @@ MacroInfo *Preprocessor::ReadOptionalMacroParameterListAndBody( return nullptr; } - // If this is a definition of a variadic C99 function-like macro, not using - // the GNU named varargs extension, enabled __VA_ARGS__. + // If this is a definition of an ISO C/C++ variadic function-like macro (not + // using the GNU named varargs extension) inform our variadic scope guard + // which un-poisons and re-poisons certain identifiers (e.g. __VA_ARGS__) + // allowed only within the definition of a variadic macro. - // "Poison" __VA_ARGS__, which can only appear in the expansion of a macro. - // This gets unpoisoned where it is allowed. - assert(Ident__VA_ARGS__->isPoisoned() && "__VA_ARGS__ should be poisoned!"); - if (MI->isC99Varargs()) - Ident__VA_ARGS__->setIsPoisoned(false); + if (MI->isC99Varargs()) { + VariadicMacroScopeGuard.enterScope(); + } // Read the first token after the arg list for down below. LexUnexpandedToken(Tok); @@ -2431,9 +2436,6 @@ MacroInfo *Preprocessor::ReadOptionalMacroParameterListAndBody( } else { Diag(Tok, diag::err_pp_stringize_not_parameter) << LastTok.is(tok::hashat); - - // Disable __VA_ARGS__ again. - Ident__VA_ARGS__->setIsPoisoned(true); return nullptr; } } @@ -2448,9 +2450,6 @@ MacroInfo *Preprocessor::ReadOptionalMacroParameterListAndBody( } } MI->setDefinitionEndLoc(LastTok.getLocation()); - // Disable __VA_ARGS__ again. - Ident__VA_ARGS__->setIsPoisoned(true); - return MI; } /// HandleDefineDirective - Implements \#define. This consumes the entire macro |
