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Improve declaration / expression disambiguation around ptr-operators, and use 

the presence of an abstract declarator with a ptr-operator as proof that a
construct cannot parse as an expression to improve diagnostics along error
recovery paths.

llvm-svn: 230261
This commit is contained in:
Richard Smith 2015-02-23 21:16:05 +00:00
parent 0168d34e23
commit 152a172899
6 changed files with 67 additions and 28 deletions
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5
clang/include/clang/Parse/Parser.h
View File

@ -1941,11 +1941,12 @@ private:
TPResult TryParsePtrOperatorSeq();
TPResult TryParseOperatorId();
TPResult TryParseInitDeclaratorList();
TPResult TryParseDeclarator(bool mayBeAbstract, bool mayHaveIdentifier=true);
TPResult TryParseDeclarator(bool MayBeAbstract, bool MayHaveIdentifier = true,
bool VersusExpression = true);
TPResult
TryParseParameterDeclarationClause(bool *InvalidAsDeclaration = nullptr,
bool VersusTemplateArg = false);
TPResult TryParseFunctionDeclarator();
TPResult TryParseFunctionDeclarator(bool VersusExpression = true);
TPResult TryParseBracketDeclarator();
TPResult TryConsumeDeclarationSpecifier();

66
clang/lib/Parse/ParseTentative.cpp
View File

@ -284,7 +284,7 @@ Parser::TPResult Parser::TryParseSimpleDeclaration(bool AllowForRangeDecl) {
Parser::TPResult Parser::TryParseInitDeclaratorList() {
while (1) {
// declarator
TPResult TPR = TryParseDeclarator(false/*mayBeAbstract*/);
TPResult TPR = TryParseDeclarator(false/*MayBeAbstract*/);
if (TPR != TPResult::Ambiguous)
return TPR;
@ -361,7 +361,7 @@ bool Parser::isCXXConditionDeclaration() {
assert(Tok.is(tok::l_paren) && "Expected '('");
// declarator
TPR = TryParseDeclarator(false/*mayBeAbstract*/);
TPR = TryParseDeclarator(false/*MayBeAbstract*/);
// In case of an error, let the declaration parsing code handle it.
if (TPR == TPResult::Error)
@ -431,7 +431,7 @@ bool Parser::isCXXTypeId(TentativeCXXTypeIdContext Context, bool &isAmbiguous) {
assert(Tok.is(tok::l_paren) && "Expected '('");
// declarator
TPR = TryParseDeclarator(true/*mayBeAbstract*/, false/*mayHaveIdentifier*/);
TPR = TryParseDeclarator(/*MayBeAbstract*/true, /*MayHaveIdentifier*/false);
// In case of an error, let the declaration parsing code handle it.
if (TPR == TPResult::Error)
@ -623,6 +623,7 @@ Parser::isCXX11AttributeSpecifier(bool Disambiguate,
}
Parser::TPResult Parser::TryParsePtrOperatorSeq() {
bool ConsumedAny = false;
while (true) {
if (Tok.is(tok::coloncolon) || Tok.is(tok::identifier))
if (TryAnnotateCXXScopeToken(true))
@ -637,8 +638,9 @@ Parser::TPResult Parser::TryParsePtrOperatorSeq() {
Tok.is(tok::kw_volatile) ||
Tok.is(tok::kw_restrict))
ConsumeToken();
ConsumedAny = true;
} else {
return TPResult::True;
return ConsumedAny ? TPResult::True : TPResult::False;
}
}
}
@ -734,7 +736,8 @@ Parser::TPResult Parser::TryParseOperatorId() {
return TPResult::Error;
AnyDeclSpecifiers = true;
}
return TryParsePtrOperatorSeq();
return TryParsePtrOperatorSeq() == TPResult::Error ? TPResult::Error
: TPResult::True;
}
/// declarator:
@ -790,13 +793,23 @@ Parser::TPResult Parser::TryParseOperatorId() {
/// '~' decltype-specifier [TODO]
/// template-id [TODO]
///
Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
bool mayHaveIdentifier) {
Parser::TPResult Parser::TryParseDeclarator(bool MayBeAbstract,
bool MayHaveIdentifier,
bool VersusExpression) {
// declarator:
// direct-declarator
// ptr-operator declarator
if (TryParsePtrOperatorSeq() == TPResult::Error)
return TPResult::Error;
{
TPResult TPR = TryParsePtrOperatorSeq();
if (TPR == TPResult::Error)
return TPResult::Error;
// After a ptr-operator, any of ')', ',', ';', and '...' indicates
// that this cannot be an expression.
if (VersusExpression && TPR == TPResult::True &&
(Tok.is(tok::r_paren) || Tok.is(tok::comma) || Tok.is(tok::ellipsis) ||
Tok.is(tok::semi)))
return TPResult::True;
}
// direct-declarator:
// direct-abstract-declarator:
@ -806,7 +819,7 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
if ((Tok.is(tok::identifier) || Tok.is(tok::kw_operator) ||
(Tok.is(tok::annot_cxxscope) && (NextToken().is(tok::identifier) ||
NextToken().is(tok::kw_operator)))) &&
mayHaveIdentifier) {
MayHaveIdentifier) {
// declarator-id
if (Tok.is(tok::annot_cxxscope))
ConsumeToken();
@ -819,14 +832,14 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
ConsumeToken();
} else if (Tok.is(tok::l_paren)) {
ConsumeParen();
if (mayBeAbstract &&
if (MayBeAbstract &&
(Tok.is(tok::r_paren) || // 'int()' is a function.
// 'int(...)' is a function.
(Tok.is(tok::ellipsis) && NextToken().is(tok::r_paren)) ||
isDeclarationSpecifier())) { // 'int(int)' is a function.
// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
// exception-specification[opt]
TPResult TPR = TryParseFunctionDeclarator();
TPResult TPR = TryParseFunctionDeclarator(VersusExpression);
if (TPR != TPResult::Ambiguous)
return TPR;
} else {
@ -842,14 +855,15 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
Tok.is(tok::kw___vectorcall) ||
Tok.is(tok::kw___unaligned))
return TPResult::True; // attributes indicate declaration
TPResult TPR = TryParseDeclarator(mayBeAbstract, mayHaveIdentifier);
TPResult TPR = TryParseDeclarator(MayBeAbstract, MayHaveIdentifier,
VersusExpression);
if (TPR != TPResult::Ambiguous)
return TPR;
if (Tok.isNot(tok::r_paren))
return TPResult::False;
ConsumeParen();
}
} else if (!mayBeAbstract) {
} else if (!MayBeAbstract) {
return TPResult::False;
}
@ -865,13 +879,13 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
// initializer that follows the declarator. Note that ctor-style
// initializers are not possible in contexts where abstract declarators
// are allowed.
if (!mayBeAbstract && !isCXXFunctionDeclarator())
if (!MayBeAbstract && !isCXXFunctionDeclarator())
break;
// direct-declarator '(' parameter-declaration-clause ')'
// cv-qualifier-seq[opt] exception-specification[opt]
ConsumeParen();
TPR = TryParseFunctionDeclarator();
TPR = TryParseFunctionDeclarator(VersusExpression);
} else if (Tok.is(tok::l_square)) {
// direct-declarator '[' constant-expression[opt] ']'
// direct-abstract-declarator[opt] '[' constant-expression[opt] ']'
@ -1710,7 +1724,8 @@ Parser::TryParseParameterDeclarationClause(bool *InvalidAsDeclaration,
// declarator
// abstract-declarator[opt]
TPR = TryParseDeclarator(true/*mayBeAbstract*/);
TPR = TryParseDeclarator(/*MayBeAbstract*/true, /*MayHaveIdentifier*/true,
/*VersusExpression*/!VersusTemplateArgument);
if (TPR != TPResult::Ambiguous)
return TPR;
@ -1757,9 +1772,15 @@ Parser::TryParseParameterDeclarationClause(bool *InvalidAsDeclaration,
/// TryParseFunctionDeclarator - We parsed a '(' and we want to try to continue
/// parsing as a function declarator.
///
/// If TryParseFunctionDeclarator fully parsed the function declarator, it will
/// return TPResult::Ambiguous, otherwise it will return either False() or
/// Error().
/// return TPResult::Ambiguous.
///
/// If \p VersusExpression is true and this cannot be a function-style
/// cast expression, returns TPResult::True.
///
/// Otherwise, returns TPResult::False if this can't be a function declarator
/// and TPResult::Error if it can't be anything.
///
/// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt]
/// exception-specification[opt]
@ -1767,7 +1788,7 @@ Parser::TryParseParameterDeclarationClause(bool *InvalidAsDeclaration,
/// exception-specification:
/// 'throw' '(' type-id-list[opt] ')'
///
Parser::TPResult Parser::TryParseFunctionDeclarator() {
Parser::TPResult Parser::TryParseFunctionDeclarator(bool VersusExpression) {
// The '(' is already parsed.
@ -1775,8 +1796,9 @@ Parser::TPResult Parser::TryParseFunctionDeclarator() {
if (TPR == TPResult::Ambiguous && Tok.isNot(tok::r_paren))
TPR = TPResult::False;
if (TPR == TPResult::False || TPR == TPResult::Error)
return TPR;
if (TPR != TPResult::Ambiguous)
if (VersusExpression || TPR != TPResult::True)
return TPR;
// Parse through the parens.
if (!SkipUntil(tok::r_paren, StopAtSemi))

9
clang/test/Parser/cxx-ambig-init-templ.cpp
View File

@ -170,6 +170,15 @@ namespace ElaboratedTypeSpecifiers {
};
}
namespace AbstractPtrOperatorDeclarator {
template <int, typename> struct X {
operator int();
};
struct Y {
void f(int a = X<0, int (*)()>());
};
}
namespace PR20459 {
template <typename EncTraits> struct A {
void foo(int = EncTraits::template TypeEnc<int, int>::val); // ok

3
clang/test/Parser/cxx-variadic-func.cpp
View File

@ -1,8 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
void f(...) {
// FIXME: There's no disambiguation here; this is unambiguous.
int g(int(...)); // expected-warning {{disambiguated}} expected-note {{paren}}
int g(int(...)); // no warning, unambiguously a function declaration
}
void h(int n..., int m); // expected-error {{expected ')'}} expected-note {{to match}}

8
clang/test/Parser/recovery.cpp
View File

@ -203,6 +203,14 @@ namespace pr15133 {
};
}
namespace AbstractPtrOperator {
// A ptr-operator and no name means we have a declaration and not an
// expression.
template<typename T> int f(int*, T::type); // expected-error {{missing 'typename'}}
template<typename T> int f(int (T::*), T::type); // expected-error {{missing 'typename'}}
template<typename T> int f(int (*)(), T::type); // expected-error {{missing 'typename'}}
}
namespace InvalidEmptyNames {
// These shouldn't crash, the diagnostics aren't important.
struct ::, struct ::; // expected-error 2 {{expected identifier}} expected-error 2 {{declaration of anonymous struct must be a definition}} expected-warning {{declaration does not declare anything}}

4
clang/test/SemaTemplate/rdar9173693.cpp
View File

@ -2,5 +2,5 @@
// <rdar://problem/9173693>
template< bool C > struct assert { };
template< bool > struct assert_arg_pred_impl { }; // expected-note 3 {{declared here}}
template< typename Pred > assert<false> assert_not_arg( void (*)(Pred), typename assert_arg_pred<Pred>::type ); // expected-error 5 {{}}
template< bool > struct assert_arg_pred_impl { }; // expected-note 2 {{declared here}}
template< typename Pred > assert<false> assert_not_arg( void (*)(Pred), typename assert_arg_pred<Pred>::type ); // expected-error 3 {{}}