[clang] 5dfa37a - Don't allow __VA_OPT__ to be detected by #ifdef.
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 27 13:34:31 PST 2021
Author: Richard Smith
Date: 2021-01-27T13:34:15-08:00
New Revision: 5dfa37a76153f2a18ac7fe30721cc1332b672ea2
URL: https://github.com/llvm/llvm-project/commit/5dfa37a76153f2a18ac7fe30721cc1332b672ea2
DIFF: https://github.com/llvm/llvm-project/commit/5dfa37a76153f2a18ac7fe30721cc1332b672ea2.diff
LOG: Don't allow __VA_OPT__ to be detected by #ifdef.
More study has discovered this to not actually be useful: because
current C++20 implementations reject `#ifdef __VA_OPT__`, this can't
really be used as a feature-test mechanism. And it's not too hard to
detect __VA_OPT__ without this, for example:
#define THIRD_ARG(a, b, c, ...) c
#define HAS_VA_OPT(...) THIRD_ARG(__VA_OPT__(,), 1, 0, )
#if HAS_VA_OPT(?)
Partially reverts 0436ec2128c9775ba13b0308937238fc79673fdd.
Added:
Modified:
clang/include/clang/Lex/Preprocessor.h
clang/lib/Lex/PPDirectives.cpp
clang/lib/Lex/PPExpressions.cpp
clang/lib/Lex/PPMacroExpansion.cpp
clang/lib/Lex/Preprocessor.cpp
clang/test/Preprocessor/macro_vaopt_check.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index ba8bdaa23c4c..68139cb24b31 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -447,25 +447,6 @@ class Preprocessor {
ElseLoc(ElseLoc) {}
};
- class IfdefMacroNameScopeRAII {
- Preprocessor &PP;
- bool VAOPTWasPoisoned;
-
- public:
- IfdefMacroNameScopeRAII(Preprocessor &PP)
- : PP(PP), VAOPTWasPoisoned(PP.Ident__VA_OPT__->isPoisoned()) {
- PP.Ident__VA_OPT__->setIsPoisoned(false);
- }
- IfdefMacroNameScopeRAII(const IfdefMacroNameScopeRAII&) = delete;
- IfdefMacroNameScopeRAII &operator=(const IfdefMacroNameScopeRAII&) = delete;
- ~IfdefMacroNameScopeRAII() { Exit(); }
-
- void Exit() {
- if (VAOPTWasPoisoned)
- PP.Ident__VA_OPT__->setIsPoisoned(true);
- }
- };
-
private:
friend class ASTReader;
friend class MacroArgs;
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index e2aa93455ea5..d6b03d85913d 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -2928,14 +2928,9 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
++NumIf;
Token DirectiveTok = Result;
- // __VA_OPT__ is allowed as the operand of #if[n]def.
- IfdefMacroNameScopeRAII IfdefMacroNameScope(*this);
-
Token MacroNameTok;
ReadMacroName(MacroNameTok);
- IfdefMacroNameScope.Exit();
-
// Error reading macro name? If so, diagnostic already issued.
if (MacroNameTok.is(tok::eod)) {
// Skip code until we get to #endif. This helps with recovery by not
diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp
index 952fb8f121dc..8c120c13d7d2 100644
--- a/clang/lib/Lex/PPExpressions.cpp
+++ b/clang/lib/Lex/PPExpressions.cpp
@@ -104,9 +104,6 @@ static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
SourceLocation beginLoc(PeekTok.getLocation());
Result.setBegin(beginLoc);
- // __VA_OPT__ is allowed as the operand of 'defined'.
- Preprocessor::IfdefMacroNameScopeRAII IfdefMacroNameScope(PP);
-
// Get the next token, don't expand it.
PP.LexUnexpandedNonComment(PeekTok);
@@ -125,8 +122,6 @@ static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
PP.LexUnexpandedNonComment(PeekTok);
}
- IfdefMacroNameScope.Exit();
-
// If we don't have a pp-identifier now, this is an error.
if (PP.CheckMacroName(PeekTok, MU_Other))
return true;
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index f6ca04defeb9..43d31d6c5732 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -323,16 +323,13 @@ void Preprocessor::dumpMacroInfo(const IdentifierInfo *II) {
/// RegisterBuiltinMacro - Register the specified identifier in the identifier
/// table and mark it as a builtin macro to be expanded.
-static IdentifierInfo *RegisterBuiltinMacro(Preprocessor &PP, const char *Name,
- bool Disabled = false) {
+static IdentifierInfo *RegisterBuiltinMacro(Preprocessor &PP, const char *Name){
// Get the identifier.
IdentifierInfo *Id = PP.getIdentifierInfo(Name);
// Mark it as being a macro that is builtin.
MacroInfo *MI = PP.AllocateMacroInfo(SourceLocation());
MI->setIsBuiltinMacro();
- if (Disabled)
- MI->DisableMacro();
PP.appendDefMacroDirective(Id, MI);
return Id;
}
@@ -346,7 +343,6 @@ void Preprocessor::RegisterBuiltinMacros() {
Ident__TIME__ = RegisterBuiltinMacro(*this, "__TIME__");
Ident__COUNTER__ = RegisterBuiltinMacro(*this, "__COUNTER__");
Ident_Pragma = RegisterBuiltinMacro(*this, "_Pragma");
- Ident__VA_OPT__ = RegisterBuiltinMacro(*this, "__VA_OPT__", true);
// C++ Standing Document Extensions.
if (getLangOpts().CPlusPlus)
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 9baba204b324..177786d90390 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -115,20 +115,19 @@ Preprocessor::Preprocessor(std::shared_ptr<PreprocessorOptions> PPOpts,
BuiltinInfo = std::make_unique<Builtin::Context>();
+ // "Poison" __VA_ARGS__, __VA_OPT__ which can only appear in the expansion of
+ // a macro. They get unpoisoned where it is allowed.
+ (Ident__VA_ARGS__ = getIdentifierInfo("__VA_ARGS__"))->setIsPoisoned();
+ SetPoisonReason(Ident__VA_ARGS__,diag::ext_pp_bad_vaargs_use);
+ (Ident__VA_OPT__ = getIdentifierInfo("__VA_OPT__"))->setIsPoisoned();
+ SetPoisonReason(Ident__VA_OPT__,diag::ext_pp_bad_vaopt_use);
+
// Initialize the pragma handlers.
RegisterBuiltinPragmas();
// Initialize builtin macros like __LINE__ and friends.
RegisterBuiltinMacros();
- // "Poison" __VA_ARGS__, __VA_OPT__ which can only appear in the expansion of
- // a macro. They get unpoisoned where it is allowed. Note that we model
- // __VA_OPT__ as a builtin macro to allow #ifdef and friends to detect it.
- (Ident__VA_ARGS__ = getIdentifierInfo("__VA_ARGS__"))->setIsPoisoned();
- SetPoisonReason(Ident__VA_ARGS__, diag::ext_pp_bad_vaargs_use);
- Ident__VA_OPT__->setIsPoisoned();
- SetPoisonReason(Ident__VA_OPT__, diag::ext_pp_bad_vaopt_use);
-
if(LangOpts.Borland) {
Ident__exception_info = getIdentifierInfo("_exception_info");
Ident___exception_info = getIdentifierInfo("__exception_info");
diff --git a/clang/test/Preprocessor/macro_vaopt_check.cpp b/clang/test/Preprocessor/macro_vaopt_check.cpp
index 84f3b85871dd..c5c0ac518bc0 100644
--- a/clang/test/Preprocessor/macro_vaopt_check.cpp
+++ b/clang/test/Preprocessor/macro_vaopt_check.cpp
@@ -2,20 +2,6 @@
// RUN: %clang_cc1 %s -Eonly -verify -Wno-all -pedantic -std=c++11
// RUN: %clang_cc1 -x c %s -Eonly -verify -Wno-all -pedantic -std=c99
-// Check that support for __VA_OPT__ can be detected by #ifdef.
-#ifndef __VA_OPT__
-#error should be defined
-#endif
-
-#ifdef __VA_OPT__
-#else
-#error should be defined
-#endif
-
-#if !defined(__VA_OPT__)
-#error should be defined
-#endif
-
//expected-error at +1{{missing '('}}
#define V1(...) __VA_OPT__
#undef V1
@@ -82,12 +68,7 @@
#if __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
#endif
-#define BAD __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
-
-// Check defined(__VA_OPT__) doesn't leave __VA_OPT__ poisoned.
-#define Z(...) (0 __VA_OPT__(|| 1))
-#if defined(__VA_OPT__) && Z(hello)
-// OK
-#else
-#error bad
+#ifdef __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
#endif
+
+#define BAD __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
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