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Improve template instantiation for object constructions in several ways: 

- During instantiation, drop default arguments from constructor and
    call expressions; they'll be recomputed anyway, and we don't want
    to instantiate them twice.
  - Rewrote the instantiation of variable initializers to cope with
    non-dependent forms properly.

Together, these fix a handful of problems I introduced with the switch
to always rebuild expressions from the source code "as written."

llvm-svn: 91315
This commit is contained in:
Douglas Gregor 2009-12-14 19:27:10 +00:00
parent fed3d088ce
commit d196a58b55
5 changed files with 180 additions and 102 deletions
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17
clang/include/clang/AST/Expr.h
View File

@ -309,6 +309,15 @@ public:
/// ParenExpr or CastExprs, returning their operand.
Expr *IgnoreParenNoopCasts(ASTContext &Ctx);
/// \brief Determine whether this expression is a default function argument.
///
/// Default arguments are implicitly generated in the abstract syntax tree
/// by semantic analysis for function calls, object constructions, etc. in
/// C++. Default arguments are represented by \c CXXDefaultArgExpr nodes;
/// this routine also looks through any implicit casts to determine whether
/// the expression is a default argument.
bool isDefaultArgument() const;
const Expr* IgnoreParens() const {
return const_cast<Expr*>(this)->IgnoreParens();
}
@ -1609,6 +1618,14 @@ public:
const Expr *getSubExpr() const { return cast<Expr>(Op); }
void setSubExpr(Expr *E) { Op = E; }
/// \brief Retrieve the cast subexpression as it was written in the source
/// code, looking through any implicit casts or other intermediate nodes
/// introduced by semantic analysis.
Expr *getSubExprAsWritten();
const Expr *getSubExprAsWritten() const {
return const_cast<CastExpr *>(this)->getSubExprAsWritten();
}
static bool classof(const Stmt *T) {
StmtClass SC = T->getStmtClass();
if (SC >= CXXNamedCastExprClass && SC <= CXXFunctionalCastExprClass)

31
clang/lib/AST/Expr.cpp
View File

@ -568,6 +568,30 @@ const char *CastExpr::getCastKindName() const {
return 0;
}
Expr *CastExpr::getSubExprAsWritten() {
Expr *SubExpr = 0;
CastExpr *E = this;
do {
SubExpr = E->getSubExpr();
// Skip any temporary bindings; they're implicit.
if (CXXBindTemporaryExpr *Binder = dyn_cast<CXXBindTemporaryExpr>(SubExpr))
SubExpr = Binder->getSubExpr();
// Conversions by constructor and conversion functions have a
// subexpression describing the call; strip it off.
if (E->getCastKind() == CastExpr::CK_ConstructorConversion)
SubExpr = cast<CXXConstructExpr>(SubExpr)->getArg(0);
else if (E->getCastKind() == CastExpr::CK_UserDefinedConversion)
SubExpr = cast<CXXMemberCallExpr>(SubExpr)->getImplicitObjectArgument();
// If the subexpression we're left with is an implicit cast, look
// through that, too.
} while ((E = dyn_cast<ImplicitCastExpr>(SubExpr)));
return SubExpr;
}
/// getOpcodeStr - Turn an Opcode enum value into the punctuation char it
/// corresponds to, e.g. "<<=".
const char *BinaryOperator::getOpcodeStr(Opcode Op) {
@ -1347,6 +1371,13 @@ Expr *Expr::IgnoreParenNoopCasts(ASTContext &Ctx) {
}
}
bool Expr::isDefaultArgument() const {
const Expr *E = this;
while (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
E = ICE->getSubExprAsWritten();
return isa<CXXDefaultArgExpr>(E);
}
/// hasAnyTypeDependentArguments - Determines if any of the expressions
/// in Exprs is type-dependent.

169
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
View File

@ -150,6 +150,35 @@ Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
return Typedef;
}
/// \brief Instantiate the arguments provided as part of initialization.
///
/// \returns true if an error occurred, false otherwise.
static bool InstantiateInitializationArguments(Sema &SemaRef,
Expr **Args, unsigned NumArgs,
const MultiLevelTemplateArgumentList &TemplateArgs,
llvm::SmallVectorImpl<SourceLocation> &FakeCommaLocs,
ASTOwningVector<&ActionBase::DeleteExpr> &InitArgs) {
for (unsigned I = 0; I != NumArgs; ++I) {
// When we hit the first defaulted argument, break out of the loop:
// we don't pass those default arguments on.
if (Args[I]->isDefaultArgument())
break;
Sema::OwningExprResult Arg = SemaRef.SubstExpr(Args[I], TemplateArgs);
if (Arg.isInvalid())
return true;
Expr *ArgExpr = (Expr *)Arg.get();
InitArgs.push_back(Arg.release());
// FIXME: We're faking all of the comma locations. Do we need them?
FakeCommaLocs.push_back(
SemaRef.PP.getLocForEndOfToken(ArgExpr->getLocEnd()));
}
return false;
}
Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
// Do substitution on the type of the declaration
TypeSourceInfo *DI = SemaRef.SubstType(D->getTypeSourceInfo(),
@ -201,78 +230,76 @@ Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
else
SemaRef.PushExpressionEvaluationContext(Sema::PotentiallyEvaluated);
OwningExprResult Init
= SemaRef.SubstExpr(D->getInit(), TemplateArgs);
if (Init.isInvalid())
Var->setInvalidDecl();
else if (ParenListExpr *PLE = dyn_cast<ParenListExpr>((Expr *)Init.get())) {
// FIXME: We're faking all of the comma locations, which is suboptimal.
// Do we even need these comma locations?
llvm::SmallVector<SourceLocation, 4> FakeCommaLocs;
if (PLE->getNumExprs() > 0) {
FakeCommaLocs.reserve(PLE->getNumExprs() - 1);
for (unsigned I = 0, N = PLE->getNumExprs() - 1; I != N; ++I) {
Expr *E = PLE->getExpr(I)->Retain();
FakeCommaLocs.push_back(
SemaRef.PP.getLocForEndOfToken(E->getLocEnd()));
}
PLE->getExpr(PLE->getNumExprs() - 1)->Retain();
}
// Add the direct initializer to the declaration.
SemaRef.AddCXXDirectInitializerToDecl(Sema::DeclPtrTy::make(Var),
PLE->getLParenLoc(),
Sema::MultiExprArg(SemaRef,
(void**)PLE->getExprs(),
PLE->getNumExprs()),
FakeCommaLocs.data(),
PLE->getRParenLoc());
// When Init is destroyed, it will destroy the instantiated ParenListExpr;
// we've explicitly retained all of its subexpressions already.
} else if (CXXConstructExpr *Construct
= dyn_cast<CXXConstructExpr>((Expr *)Init.get())) {
// We build CXXConstructExpr nodes to capture the implicit
// construction of objects. Rip apart the CXXConstructExpr to
// pass its pieces down to the appropriate initialization
// function.
if (D->hasCXXDirectInitializer()) {
// FIXME: Poor source location information
SourceLocation FakeLParenLoc =
SemaRef.PP.getLocForEndOfToken(D->getLocation());
SourceLocation FakeRParenLoc = FakeLParenLoc;
llvm::SmallVector<SourceLocation, 4> FakeCommaLocs;
if (Construct->getNumArgs() > 0) {
FakeRParenLoc
= SemaRef.PP.getLocForEndOfToken(
Construct->getArg(Construct->getNumArgs() - 1)->getLocEnd());
FakeCommaLocs.reserve(Construct->getNumArgs() - 1);
for (unsigned I = 0, N = Construct->getNumArgs() - 1; I != N; ++I) {
Expr *E = Construct->getArg(I)->Retain();
FakeCommaLocs.push_back(
SemaRef.PP.getLocForEndOfToken(E->getLocEnd()));
}
Construct->getArg(Construct->getNumArgs() - 1)->Retain();
}
// Extract the initializer, skipping through any temporary-binding
// expressions and look at the subexpression as it was written.
Expr *DInit = D->getInit();
while (CXXBindTemporaryExpr *Binder = dyn_cast<CXXBindTemporaryExpr>(DInit))
DInit = Binder->getSubExpr();
if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(DInit))
DInit = ICE->getSubExprAsWritten();
if (ParenListExpr *PLE = dyn_cast<ParenListExpr>(DInit)) {
// The initializer is a parenthesized list of expressions that is
// type-dependent. Instantiate each of the expressions; we'll be
// performing direct initialization with them.
llvm::SmallVector<SourceLocation, 4> CommaLocs;
ASTOwningVector<&ActionBase::DeleteExpr> InitArgs(SemaRef);
if (!InstantiateInitializationArguments(SemaRef,
PLE->getExprs(),
PLE->getNumExprs(),
TemplateArgs,
CommaLocs, InitArgs)) {
// Add the direct initializer to the declaration.
SemaRef.AddCXXDirectInitializerToDecl(Sema::DeclPtrTy::make(Var),
FakeLParenLoc,
Sema::MultiExprArg(SemaRef,
(void **)Construct->getArgs(),
Construct->getNumArgs()),
FakeCommaLocs.data(),
FakeRParenLoc);
} else if (Construct->getNumArgs() >= 1) {
SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var),
SemaRef.Owned(Construct->getArg(0)->Retain()),
false);
} else
SemaRef.ActOnUninitializedDecl(Sema::DeclPtrTy::make(Var), false);
} else
SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var), move(Init),
D->hasCXXDirectInitializer());
PLE->getLParenLoc(),
move_arg(InitArgs),
CommaLocs.data(),
PLE->getRParenLoc());
}
} else if (CXXConstructExpr *Construct =dyn_cast<CXXConstructExpr>(DInit)) {
// The initializer resolved to a constructor. Instantiate the constructor
// arguments.
llvm::SmallVector<SourceLocation, 4> CommaLocs;
ASTOwningVector<&ActionBase::DeleteExpr> InitArgs(SemaRef);
if (!InstantiateInitializationArguments(SemaRef,
Construct->getArgs(),
Construct->getNumArgs(),
TemplateArgs,
CommaLocs, InitArgs)) {
if (D->hasCXXDirectInitializer()) {
SourceLocation FakeLParenLoc =
SemaRef.PP.getLocForEndOfToken(D->getLocation());
SourceLocation FakeRParenLoc = CommaLocs.empty()? FakeLParenLoc
: CommaLocs.back();
SemaRef.AddCXXDirectInitializerToDecl(Sema::DeclPtrTy::make(Var),
FakeLParenLoc,
move_arg(InitArgs),
CommaLocs.data(),
FakeRParenLoc);
} else if (InitArgs.size() == 1) {
Expr *Init = (Expr*)(InitArgs.take()[0]);
SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var),
SemaRef.Owned(Init),
false);
} else {
assert(InitArgs.size() == 0);
SemaRef.ActOnUninitializedDecl(Sema::DeclPtrTy::make(Var), false);
}
}
} else {
OwningExprResult Init
= SemaRef.SubstExpr(D->getInit(), TemplateArgs);
// FIXME: Not happy about invalidating decls just because of a bad
// initializer, unless it affects the type.
if (Init.isInvalid())
Var->setInvalidDecl();
else
SemaRef.AddInitializerToDecl(Sema::DeclPtrTy::make(Var), move(Init),
D->hasCXXDirectInitializer());
}
SemaRef.PopExpressionEvaluationContext();
} else if (!Var->isStaticDataMember() || Var->isOutOfLine())
SemaRef.ActOnUninitializedDecl(Sema::DeclPtrTy::make(Var), false);

53
clang/lib/Sema/TreeTransform.h
View File

@ -172,6 +172,16 @@ public:
return T.isNull();
}
/// \brief Determine whether the given call argument should be dropped, e.g.,
/// because it is a default argument.
///
/// Subclasses can provide an alternative implementation of this routine to
/// determine which kinds of call arguments get dropped. By default,
/// CXXDefaultArgument nodes are dropped (prior to transformation).
bool DropCallArgument(Expr *E) {
return E->isDefaultArgument();
}
/// \brief Transforms the given type into another type.
///
/// By default, this routine transforms a type by creating a
@ -3770,39 +3780,12 @@ TreeTransform<Derived>::TransformConditionalOperator(ConditionalOperator *E) {
move(RHS));
}
/// \brief Given a cast expression, extract the subexpression of the
/// cast, looking through intermediate AST nodes that were generated
/// as part of type checking.
static Expr *getCastSubExprAsWritten(CastExpr *E) {
Expr *SubExpr = 0;
do {
SubExpr = E->getSubExpr();
// Temporaries will be re-bound when rebuilding the original cast
// expression.
if (CXXBindTemporaryExpr *Binder = dyn_cast<CXXBindTemporaryExpr>(SubExpr))
SubExpr = Binder->getSubExpr();
// Conversions by constructor and conversion functions have a
// subexpression describing the call; strip it off.
if (E->getCastKind() == CastExpr::CK_ConstructorConversion)
SubExpr = cast<CXXConstructExpr>(SubExpr)->getArg(0);
else if (E->getCastKind() == CastExpr::CK_UserDefinedConversion)
SubExpr = cast<CXXMemberCallExpr>(SubExpr)->getImplicitObjectArgument();
// If the subexpression we're left with is an implicit cast, look
// through that, too.
} while ((E = dyn_cast<ImplicitCastExpr>(SubExpr)));
return SubExpr;
}
template<typename Derived>
Sema::OwningExprResult
TreeTransform<Derived>::TransformImplicitCastExpr(ImplicitCastExpr *E) {
// Implicit casts are eliminated during transformation, since they
// will be recomputed by semantic analysis after transformation.
return getDerived().TransformExpr(getCastSubExprAsWritten(E));
return getDerived().TransformExpr(E->getSubExprAsWritten());
}
template<typename Derived>
@ -3828,7 +3811,7 @@ TreeTransform<Derived>::TransformCStyleCastExpr(CStyleCastExpr *E) {
}
OwningExprResult SubExpr
= getDerived().TransformExpr(getCastSubExprAsWritten(E));
= getDerived().TransformExpr(E->getSubExprAsWritten());
if (SubExpr.isInvalid())
return SemaRef.ExprError();
@ -4161,6 +4144,9 @@ TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
ASTOwningVector<&ActionBase::DeleteExpr> Args(SemaRef);
llvm::SmallVector<SourceLocation, 4> FakeCommaLocs;
for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
if (getDerived().DropCallArgument(E->getArg(I)))
break;
OwningExprResult Arg = getDerived().TransformExpr(E->getArg(I));
if (Arg.isInvalid())
return SemaRef.ExprError();
@ -4247,7 +4233,7 @@ TreeTransform<Derived>::TransformCXXNamedCastExpr(CXXNamedCastExpr *E) {
}
OwningExprResult SubExpr
= getDerived().TransformExpr(getCastSubExprAsWritten(E));
= getDerived().TransformExpr(E->getSubExprAsWritten());
if (SubExpr.isInvalid())
return SemaRef.ExprError();
@ -4312,7 +4298,7 @@ TreeTransform<Derived>::TransformCXXFunctionalCastExpr(
}
OwningExprResult SubExpr
= getDerived().TransformExpr(getCastSubExprAsWritten(E));
= getDerived().TransformExpr(E->getSubExprAsWritten());
if (SubExpr.isInvalid())
return SemaRef.ExprError();
@ -4713,6 +4699,11 @@ TreeTransform<Derived>::TransformCXXConstructExpr(CXXConstructExpr *E) {
for (CXXConstructExpr::arg_iterator Arg = E->arg_begin(),
ArgEnd = E->arg_end();
Arg != ArgEnd; ++Arg) {
if (getDerived().DropCallArgument(*Arg)) {
ArgumentChanged = true;
break;
}
OwningExprResult TransArg = getDerived().TransformExpr(*Arg);
if (TransArg.isInvalid())
return SemaRef.ExprError();

12
clang/test/SemaTemplate/constructor-template.cpp
View File

@ -82,3 +82,15 @@ X4 test_X4(bool Cond, X4 x4) {
X4 b(x4); // okay, copy constructor
return X4(); // expected-error{{no viable conversion}}
}
// Instantiation of a non-dependent use of a constructor
struct DefaultCtorHasDefaultArg {
explicit DefaultCtorHasDefaultArg(int i = 17);
};
template<typename T>
void default_ctor_inst() {
DefaultCtorHasDefaultArg def;
}
template void default_ctor_inst<int>();