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Revert D123909 "[Clang] Use of decltype(capture) in parameter-declaration-clause" 

This reverts commit daa6d7b250.

It breaks valid code like https://reviews.llvm.org/D123909#3461716
This commit is contained in:
Fangrui Song 2022-04-20 10:32:41 -07:00
parent 9955f14aaf
commit 0f5dbfd29a
7 changed files with 12 additions and 93 deletions
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2
clang/docs/ReleaseNotes.rst
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@ -281,8 +281,6 @@ C++2b Feature Support
- Implemented `P2036R3: Change scope of lambda trailing-return-type <https://wg21.link/P2036R3>`_.
This proposal modifies how variables captured in lambdas can appear in trailing return type
expressions and how their types are deduced therein, in all C++ language versions.
`CWG2569 <https://cplusplus.github.io/CWG/issues/2569.html>`_ is also partially implemented so that
`[x](decltype(x)){}` doesn't become ill-formed with the adoption of P2036R3.
CUDA Language Changes in Clang
------------------------------

2
clang/include/clang/Parse/Parser.h
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@ -1861,8 +1861,6 @@ private:
Token &Replacement);
ExprResult ParseCXXIdExpression(bool isAddressOfOperand = false);
ExprResult ParseCXXMaybeMutableAgnosticExpression();
bool areTokensAdjacent(const Token &A, const Token &B);
void CheckForTemplateAndDigraph(Token &Next, ParsedType ObjectTypePtr,

20
clang/include/clang/Sema/Sema.h
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@ -787,23 +787,6 @@ public:
/// context.
unsigned FunctionScopesStart = 0;
/// Whether we are currently in the context of a mutable agnostic identifier
/// as described by CWG2569.
/// We are handling the unqualified-id of a decltype or noexcept expression.
bool InMutableAgnosticContext = false;
/// RAII object used to change the value of \c InMutableAgnosticContext
/// within a \c Sema object.
class MutableAgnosticContextRAII {
Sema &SemaRef;
public:
MutableAgnosticContextRAII(Sema &S) : SemaRef(S) {
SemaRef.InMutableAgnosticContext = true;
}
~MutableAgnosticContextRAII() { SemaRef.InMutableAgnosticContext = false; }
};
ArrayRef<sema::FunctionScopeInfo*> getFunctionScopes() const {
return llvm::makeArrayRef(FunctionScopes.begin() + FunctionScopesStart,
FunctionScopes.end());
@ -5287,9 +5270,6 @@ public:
CorrectionCandidateCallback *CCC = nullptr,
bool IsInlineAsmIdentifier = false, Token *KeywordReplacement = nullptr);
ExprResult ActOnMutableAgnosticIdExpression(Scope *S, CXXScopeSpec &SS,
UnqualifiedId &Id);
void DecomposeUnqualifiedId(const UnqualifiedId &Id,
TemplateArgumentListInfo &Buffer,
DeclarationNameInfo &NameInfo,

2
clang/lib/Parse/ParseDeclCXX.cpp
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@ -1054,7 +1054,7 @@ SourceLocation Parser::ParseDecltypeSpecifier(DeclSpec &DS) {
Actions, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
Sema::ExpressionEvaluationContextRecord::EK_Decltype);
Result = Actions.CorrectDelayedTyposInExpr(
ParseCXXMaybeMutableAgnosticExpression(), /*InitDecl=*/nullptr,
ParseExpression(), /*InitDecl=*/nullptr,
/*RecoverUncorrectedTypos=*/false,
[](Expr *E) { return E->hasPlaceholderType() ? ExprError() : E; });
if (Result.isInvalid()) {

28
clang/lib/Parse/ParseExprCXX.cpp
View File

@ -685,34 +685,6 @@ ExprResult Parser::ParseCXXIdExpression(bool isAddressOfOperand) {
return Result;
}
/// ParseCXXMaybeMutableAgnosticExpression - Handle expressions inside of
/// sizeof, decltype, noexcept
/// - unqualified-id
/// - expression
/// This serves to silence errors about captured variable referred in lambda
/// parameter list, if they are used as the unqualified-id of a decltype,
/// sizeof, or noexcept expression.
ExprResult Parser::ParseCXXMaybeMutableAgnosticExpression() {
if (!getLangOpts().CPlusPlus11)
return ParseExpression();
if (Tok.is(tok::identifier) && NextToken().is(tok::r_paren)) {
UnqualifiedId Name;
CXXScopeSpec SS;
if (ParseUnqualifiedId(SS, /*ObjectType=*/nullptr,
/*ObjectHadErrors=*/false,
/*EnteringContext=*/false,
/*AllowDestructorName=*/false,
/*AllowConstructorName=*/false,
/*AllowDeductionGuide=*/false,
/*TemplateKWLoc=*/nullptr, Name))
return ExprError();
return Actions.ActOnMutableAgnosticIdExpression(getCurScope(), SS, Name);
}
return ParseExpression();
}
/// ParseLambdaExpression - Parse a C++11 lambda expression.
///
/// lambda-expression:

19
clang/lib/Sema/SemaExpr.cpp
View File

@ -2699,18 +2699,6 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
return BuildDeclarationNameExpr(SS, R, ADL);
}
ExprResult Sema::ActOnMutableAgnosticIdExpression(Scope *S, CXXScopeSpec &SS,
UnqualifiedId &Id) {
MutableAgnosticContextRAII Ctx(*this);
return ActOnIdExpression(S, SS, /*TemplateKwLoc*/
SourceLocation(), Id,
/*HasTrailingLParen*/ false,
/*IsAddressOfOperand*/ false,
/*CorrectionCandidateCallback*/ nullptr,
/*IsInlineAsmIdentifier*/ false,
/*KeywordReplacement*/ nullptr);
}
/// BuildQualifiedDeclarationNameExpr - Build a C++ qualified
/// declaration name, generally during template instantiation.
/// There's a large number of things which don't need to be done along
@ -18561,11 +18549,6 @@ static void buildLambdaCaptureFixit(Sema &Sema, LambdaScopeInfo *LSI,
static bool CheckCaptureUseBeforeLambdaQualifiers(Sema &S, VarDecl *Var,
SourceLocation ExprLoc,
LambdaScopeInfo *LSI) {
// Allow `[a = 1](decltype(a)) {}` as per CWG2569.
if (S.InMutableAgnosticContext)
return true;
if (Var->isInvalidDecl())
return false;
@ -18648,7 +18631,7 @@ bool Sema::tryCaptureVariable(
LSI = dyn_cast_or_null<LambdaScopeInfo>(
FunctionScopes[FunctionScopesIndex]);
if (LSI && LSI->BeforeLambdaQualifiersScope) {
if (isa<ParmVarDecl>(Var) && !Var->getDeclContext()->isFunctionOrMethod())
if (isa<ParmVarDecl>(Var))
return true;
IsInLambdaBeforeQualifiers = true;
if (!CheckCaptureUseBeforeLambdaQualifiers(*this, Var, ExprLoc, LSI)) {

32
clang/test/SemaCXX/lambda-capture-type-deduction.cpp
View File

@ -87,23 +87,23 @@ void err() {
int y, z; // expected-note 2{{declared here}}
auto implicit_tpl = [=]( // expected-note {{variable 'y' is captured here}}
decltype(
[&]<decltype((y))> { return 0; }) y) { // expected-error{{captured variable 'y' cannot appear here}}
[&]<decltype(y)> { return 0; }) y) { //expected-error{{captured variable 'y' cannot appear here}}
return y;
};
auto init_tpl = [x = 1]( // expected-note{{explicitly captured here}}
decltype([&]<decltype((x))> { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}}
auto init_tpl = [x = 1]( // expected-note{{explicitly captured here}}
decltype([&]<decltype(x)> { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}}
return x;
};
auto implicit = [=]( // expected-note {{variable 'z' is captured here}}
decltype(
[&](decltype((z))) { return 0; }) z) { // expected-error{{captured variable 'z' cannot appear here}}
[&](decltype(z)) { return 0; }) z) { //expected-error{{captured variable 'z' cannot appear here}}
return z;
};
auto init = [x = 1]( // expected-note{{explicitly captured here}}
decltype([&](decltype((x))) { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}}
auto init = [x = 1]( // expected-note{{explicitly captured here}}
decltype([&](decltype(x)) { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}}
return x;
};
@ -141,20 +141,20 @@ void nested() {
decltype([&](
decltype([=]( // expected-note {{variable 'x' is captured here}}
decltype([&](
decltype([&](decltype((x))) {}) // expected-error{{captured variable 'x' cannot appear here}}
decltype([&](decltype(x)) {}) // expected-error{{captured variable 'x' cannot appear here}}
) {})) {})) {})){};
(void)[&](
decltype([&](
decltype([&](
decltype([&](
decltype([&](decltype((y))) {})) {})) {})) {})){};
decltype([&](decltype(y)) {})) {})) {})) {})){};
(void)[=](
decltype([=](
decltype([=](
decltype([=]( // expected-note {{variable 'z' is captured here}}
decltype([&]<decltype((z))> {}) // expected-error{{captured variable 'z' cannot appear here}}
decltype([=]( // expected-note {{variable 'z' is captured here}}
decltype([&]<decltype(z)> {}) // expected-error{{captured variable 'z' cannot appear here}}
) {})) {})) {})){};
}
@ -202,15 +202,3 @@ void test_dependent() {
dependent_init_capture(0);
dependent_variadic_capture(1, 2, 3, 4);
}
void test_CWG2569_tpl(auto a) {
(void)[=]<typename T = decltype(a)>(decltype(a) b = decltype(a)()){};
}
void test_CWG2569() {
int a = 0;
(void)[=]<typename T = decltype(a)>(decltype(a) b = decltype(a)()){};
test_CWG2569_tpl(0);
(void)[=]<typename T = decltype(not_a_thing)>(decltype(not_a_thing)){}; // expected-error 2{{use of undeclared identifier 'not_a_thing'}}
}