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Refactor the way we handle diagnosing unused expression results.

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Rather than sprinkle calls to DiagnoseUnusedExprResult() around in places where we want diagnostics, we now diagnose unused expression statements and full expressions in a more generic way when acting on the final expression statement. This results in more appropriate diagnostics for [[nodiscard]] where we were previously lacking them, such as when the body of a for loop is not a compound statement.

This patch fixes PR39837.

llvm-svn: 350404
This commit is contained in:
Aaron Ballman 2019-01-04 16:58:14 +00:00
parent c2054144ee
commit fb6deeb984
21 changed files with 196 additions and 122 deletions
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5
clang/include/clang/Parse/Parser.h
View File

@ -360,6 +360,11 @@ class Parser : public CodeCompletionHandler {
/// just a regular sub-expression.
SourceLocation ExprStatementTokLoc;
/// Tests whether an expression value is discarded based on token lookahead.
/// It will return true if the lexer is currently processing the })
/// terminating a GNU statement expression and false otherwise.
bool isExprValueDiscarded();
public:
Parser(Preprocessor &PP, Sema &Actions, bool SkipFunctionBodies);
~Parser() override;

19
clang/include/clang/Sema/Sema.h
View File

@ -1365,6 +1365,7 @@ public:
void PopCompoundScope();
sema::CompoundScopeInfo &getCurCompoundScope() const;
bool isCurCompoundStmtAStmtExpr() const;
bool hasAnyUnrecoverableErrorsInThisFunction() const;
@ -3685,16 +3686,17 @@ public:
return MakeFullExpr(Arg, Arg ? Arg->getExprLoc() : SourceLocation());
}
FullExprArg MakeFullExpr(Expr *Arg, SourceLocation CC) {
return FullExprArg(ActOnFinishFullExpr(Arg, CC).get());
return FullExprArg(
ActOnFinishFullExpr(Arg, CC, /*DiscardedValue*/ false).get());
}
FullExprArg MakeFullDiscardedValueExpr(Expr *Arg) {
ExprResult FE =
ActOnFinishFullExpr(Arg, Arg ? Arg->getExprLoc() : SourceLocation(),
/*DiscardedValue*/ true);
ActOnFinishFullExpr(Arg, Arg ? Arg->getExprLoc() : SourceLocation(),
/*DiscardedValue*/ true);
return FullExprArg(FE.get());
}
StmtResult ActOnExprStmt(ExprResult Arg);
StmtResult ActOnExprStmt(ExprResult Arg, bool DiscardedValue = true);
StmtResult ActOnExprStmtError();
StmtResult ActOnNullStmt(SourceLocation SemiLoc,
@ -5340,13 +5342,12 @@ public:
CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
bool BoundToLvalueReference);
ExprResult ActOnFinishFullExpr(Expr *Expr) {
return ActOnFinishFullExpr(Expr, Expr ? Expr->getExprLoc()
: SourceLocation());
ExprResult ActOnFinishFullExpr(Expr *Expr, bool DiscardedValue) {
return ActOnFinishFullExpr(
Expr, Expr ? Expr->getExprLoc() : SourceLocation(), DiscardedValue);
}
ExprResult ActOnFinishFullExpr(Expr *Expr, SourceLocation CC,
bool DiscardedValue = false,
bool IsConstexpr = false);
bool DiscardedValue, bool IsConstexpr = false);
StmtResult ActOnFinishFullStmt(Stmt *Stmt);
// Marks SS invalid if it represents an incomplete type.

2
clang/lib/Parse/ParseObjc.cpp
View File

@ -2741,7 +2741,7 @@ StmtResult Parser::ParseObjCAtStatement(SourceLocation AtLoc) {
// Otherwise, eat the semicolon.
ExpectAndConsumeSemi(diag::err_expected_semi_after_expr);
return Actions.ActOnExprStmt(Res);
return Actions.ActOnExprStmt(Res, isExprValueDiscarded());
}
ExprResult Parser::ParseObjCAtExpression(SourceLocation AtLoc) {

14
clang/lib/Parse/ParseOpenMP.cpp
View File

@ -314,7 +314,7 @@ Parser::ParseOpenMPDeclareReductionDirective(AccessSpecifier AS) {
Actions.ActOnOpenMPDeclareReductionCombinerStart(getCurScope(), D);
ExprResult CombinerResult =
Actions.ActOnFinishFullExpr(ParseAssignmentExpression().get(),
D->getLocation(), /*DiscardedValue=*/true);
D->getLocation(), /*DiscardedValue*/ false);
Actions.ActOnOpenMPDeclareReductionCombinerEnd(D, CombinerResult.get());
if (CombinerResult.isInvalid() && Tok.isNot(tok::r_paren) &&
@ -356,7 +356,7 @@ Parser::ParseOpenMPDeclareReductionDirective(AccessSpecifier AS) {
if (Actions.getLangOpts().CPlusPlus) {
InitializerResult = Actions.ActOnFinishFullExpr(
ParseAssignmentExpression().get(), D->getLocation(),
/*DiscardedValue=*/true);
/*DiscardedValue*/ false);
} else {
ConsumeToken();
ParseOpenMPReductionInitializerForDecl(OmpPrivParm);
@ -364,7 +364,7 @@ Parser::ParseOpenMPDeclareReductionDirective(AccessSpecifier AS) {
} else {
InitializerResult = Actions.ActOnFinishFullExpr(
ParseAssignmentExpression().get(), D->getLocation(),
/*DiscardedValue=*/true);
/*DiscardedValue*/ false);
}
Actions.ActOnOpenMPDeclareReductionInitializerEnd(
D, InitializerResult.get(), OmpPrivParm);
@ -1455,7 +1455,7 @@ ExprResult Parser::ParseOpenMPParensExpr(StringRef ClauseName,
ExprResult LHS(ParseCastExpression(
/*isUnaryExpression=*/false, /*isAddressOfOperand=*/false, NotTypeCast));
ExprResult Val(ParseRHSOfBinaryExpression(LHS, prec::Conditional));
Val = Actions.ActOnFinishFullExpr(Val.get(), ELoc);
Val = Actions.ActOnFinishFullExpr(Val.get(), ELoc, /*DiscardedValue*/ false);
// Parse ')'.
RLoc = Tok.getLocation();
@ -1711,7 +1711,8 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPClauseKind Kind,
SourceLocation ELoc = Tok.getLocation();
ExprResult LHS(ParseCastExpression(false, false, NotTypeCast));
Val = ParseRHSOfBinaryExpression(LHS, prec::Conditional);
Val = Actions.ActOnFinishFullExpr(Val.get(), ELoc);
Val =
Actions.ActOnFinishFullExpr(Val.get(), ELoc, /*DiscardedValue*/ false);
}
// Parse ')'.
@ -1996,7 +1997,8 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
Data.ColonLoc = Tok.getLocation();
SourceLocation ELoc = ConsumeToken();
ExprResult Tail = ParseAssignmentExpression();
Tail = Actions.ActOnFinishFullExpr(Tail.get(), ELoc);
Tail =
Actions.ActOnFinishFullExpr(Tail.get(), ELoc, /*DiscardedValue*/ false);
if (Tail.isUsable())
Data.TailExpr = Tail.get();
else

26
clang/lib/Parse/ParseStmt.cpp
View File

@ -439,7 +439,7 @@ StmtResult Parser::ParseExprStatement() {
// Otherwise, eat the semicolon.
ExpectAndConsumeSemi(diag::err_expected_semi_after_expr);
return Actions.ActOnExprStmt(Expr);
return Actions.ActOnExprStmt(Expr, isExprValueDiscarded());
}
/// ParseSEHTryBlockCommon
@ -958,6 +958,16 @@ bool Parser::ConsumeNullStmt(StmtVector &Stmts) {
return true;
}
bool Parser::isExprValueDiscarded() {
if (Actions.isCurCompoundStmtAStmtExpr()) {
// Look to see if the next two tokens close the statement expression;
// if so, this expression statement is the last statement in a
// statment expression.
return Tok.isNot(tok::r_brace) || NextToken().isNot(tok::r_paren);
}
return true;
}
/// ParseCompoundStatementBody - Parse a sequence of statements and invoke the
/// ActOnCompoundStmt action. This expects the '{' to be the current token, and
/// consume the '}' at the end of the block. It does not manipulate the scope
@ -1062,7 +1072,7 @@ StmtResult Parser::ParseCompoundStatementBody(bool isStmtExpr) {
// Eat the semicolon at the end of stmt and convert the expr into a
// statement.
ExpectAndConsumeSemi(diag::err_expected_semi_after_expr);
R = Actions.ActOnExprStmt(Res);
R = Actions.ActOnExprStmt(Res, isExprValueDiscarded());
}
}
@ -1698,8 +1708,16 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
if (!Value.isInvalid()) {
if (ForEach)
FirstPart = Actions.ActOnForEachLValueExpr(Value.get());
else
FirstPart = Actions.ActOnExprStmt(Value);
else {
// We already know this is not an init-statement within a for loop, so
// if we are parsing a C++11 range-based for loop, we should treat this
// expression statement as being a discarded value expression because
// we will err below. This way we do not warn on an unused expression
// that was an error in the first place, like with: for (expr : expr);
bool IsRangeBasedFor =
getLangOpts().CPlusPlus11 && !ForEach && Tok.is(tok::colon);
FirstPart = Actions.ActOnExprStmt(Value, !IsRangeBasedFor);
}
}
if (Tok.is(tok::semi)) {

17
clang/lib/Sema/SemaCoroutine.cpp
View File

@ -647,7 +647,7 @@ bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
return StmtError();
Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
/*IsImplicit*/ true);
Suspend = ActOnFinishFullExpr(Suspend.get());
Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
if (Suspend.isInvalid()) {
Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
<< ((Name == "initial_suspend") ? 0 : 1);
@ -868,7 +868,7 @@ StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
if (PC.isInvalid())
return StmtError();
Expr *PCE = ActOnFinishFullExpr(PC.get()).get();
Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();
Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
return Res;
@ -1237,7 +1237,7 @@ bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
ExprResult NewExpr =
S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
NewExpr = S.ActOnFinishFullExpr(NewExpr.get());
NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
if (NewExpr.isInvalid())
return false;
@ -1263,7 +1263,8 @@ bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
ExprResult DeleteExpr =
S.ActOnCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
DeleteExpr = S.ActOnFinishFullExpr(DeleteExpr.get());
DeleteExpr =
S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
if (DeleteExpr.isInvalid())
return false;
@ -1348,7 +1349,8 @@ bool CoroutineStmtBuilder::makeOnException() {
ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
"unhandled_exception", None);
UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc);
UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc,
/*DiscardedValue*/ false);
if (UnhandledException.isInvalid())
return false;
@ -1401,7 +1403,8 @@ bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
"get_return_object type must no longer be dependent");
if (FnRetType->isVoidType()) {
ExprResult Res = S.ActOnFinishFullExpr(this->ReturnValue, Loc);
ExprResult Res =
S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false);
if (Res.isInvalid())
return false;
@ -1433,7 +1436,7 @@ bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
if (Res.isInvalid())
return false;
Res = S.ActOnFinishFullExpr(Res.get());
Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
if (Res.isInvalid())
return false;

6
clang/lib/Sema/SemaDecl.cpp
View File

@ -11204,9 +11204,9 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
// struct T { S a, b; } t = { Temp(), Temp() }
//
// we should destroy the first Temp before constructing the second.
ExprResult Result = ActOnFinishFullExpr(Init, VDecl->getLocation(),
false,
VDecl->isConstexpr());
ExprResult Result =
ActOnFinishFullExpr(Init, VDecl->getLocation(),
/*DiscardedValue*/ false, VDecl->isConstexpr());
if (Result.isInvalid()) {
VDecl->setInvalidDecl();
return;

14
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -1205,7 +1205,7 @@ static bool checkTupleLikeDecomposition(Sema &S,
E = Seq.Perform(S, Entity, Kind, Init);
if (E.isInvalid())
return true;
E = S.ActOnFinishFullExpr(E.get(), Loc);
E = S.ActOnFinishFullExpr(E.get(), Loc, /*DiscardedValue*/ false);
if (E.isInvalid())
return true;
RefVD->setInit(E.get());
@ -3682,7 +3682,7 @@ void Sema::ActOnFinishCXXInClassMemberInitializer(Decl *D,
// C++11 [class.base.init]p7:
// The initialization of each base and member constitutes a
// full-expression.
Init = ActOnFinishFullExpr(Init.get(), InitLoc);
Init = ActOnFinishFullExpr(Init.get(), InitLoc, /*DiscardedValue*/ false);
if (Init.isInvalid()) {
FD->setInvalidDecl();
return;
@ -4040,7 +4040,8 @@ Sema::BuildMemberInitializer(ValueDecl *Member, Expr *Init,
// C++11 [class.base.init]p7:
// The initialization of each base and member constitutes a
// full-expression.
MemberInit = ActOnFinishFullExpr(MemberInit.get(), InitRange.getBegin());
MemberInit = ActOnFinishFullExpr(MemberInit.get(), InitRange.getBegin(),
/*DiscardedValue*/ false);
if (MemberInit.isInvalid())
return true;
@ -4095,8 +4096,8 @@ Sema::BuildDelegatingInitializer(TypeSourceInfo *TInfo, Expr *Init,
// C++11 [class.base.init]p7:
// The initialization of each base and member constitutes a
// full-expression.
DelegationInit = ActOnFinishFullExpr(DelegationInit.get(),
InitRange.getBegin());
DelegationInit = ActOnFinishFullExpr(
DelegationInit.get(), InitRange.getBegin(), /*DiscardedValue*/ false);
if (DelegationInit.isInvalid())
return true;
@ -4225,7 +4226,8 @@ Sema::BuildBaseInitializer(QualType BaseType, TypeSourceInfo *BaseTInfo,
// C++11 [class.base.init]p7:
// The initialization of each base and member constitutes a
// full-expression.
BaseInit = ActOnFinishFullExpr(BaseInit.get(), InitRange.getBegin());
BaseInit = ActOnFinishFullExpr(BaseInit.get(), InitRange.getBegin(),
/*DiscardedValue*/ false);
if (BaseInit.isInvalid())
return true;

5
clang/lib/Sema/SemaExpr.cpp
View File

@ -4736,8 +4736,9 @@ bool Sema::CheckCXXDefaultArgExpr(SourceLocation CallLoc, FunctionDecl *FD,
if (Result.isInvalid())
return true;
Result = ActOnFinishFullExpr(Result.getAs<Expr>(),
Param->getOuterLocStart());
Result =
ActOnFinishFullExpr(Result.getAs<Expr>(), Param->getOuterLocStart(),
/*DiscardedValue*/ false);
if (Result.isInvalid())
return true;

2
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -7803,6 +7803,8 @@ ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
FullExpr = IgnoredValueConversions(FullExpr.get());
if (FullExpr.isInvalid())
return ExprError();
DiagnoseUnusedExprResult(FullExpr.get());
}
FullExpr = CorrectDelayedTyposInExpr(FullExpr.get());

2
clang/lib/Sema/SemaLambda.cpp
View File

@ -1724,7 +1724,7 @@ ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
/*NRVO=*/false),
CurrentLocation, Src);
if (!Init.isInvalid())
Init = ActOnFinishFullExpr(Init.get());
Init = ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
if (Init.isInvalid())
return ExprError();

55
clang/lib/Sema/SemaOpenMP.cpp
View File

@ -5320,7 +5320,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
LastIteration.get(), UB.get());
EUB = SemaRef.BuildBinOp(CurScope, InitLoc, BO_Assign, UB.get(),
CondOp.get());
EUB = SemaRef.ActOnFinishFullExpr(EUB.get());
EUB = SemaRef.ActOnFinishFullExpr(EUB.get(), /*DiscardedValue*/ false);
// If we have a combined directive that combines 'distribute', 'for' or
// 'simd' we need to be able to access the bounds of the schedule of the
@ -5349,7 +5349,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
LastIteration.get(), CombUB.get());
CombEUB = SemaRef.BuildBinOp(CurScope, InitLoc, BO_Assign, CombUB.get(),
CombCondOp.get());
CombEUB = SemaRef.ActOnFinishFullExpr(CombEUB.get());
CombEUB =
SemaRef.ActOnFinishFullExpr(CombEUB.get(), /*DiscardedValue*/ false);
const CapturedDecl *CD = cast<CapturedStmt>(AStmt)->getCapturedDecl();
// We expect to have at least 2 more parameters than the 'parallel'
@ -5383,7 +5384,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
? LB.get()
: SemaRef.ActOnIntegerConstant(SourceLocation(), 0).get();
Init = SemaRef.BuildBinOp(CurScope, InitLoc, BO_Assign, IV.get(), RHS);
Init = SemaRef.ActOnFinishFullExpr(Init.get());
Init = SemaRef.ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
if (isOpenMPLoopBoundSharingDirective(DKind)) {
Expr *CombRHS =
@ -5394,7 +5395,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
: SemaRef.ActOnIntegerConstant(SourceLocation(), 0).get();
CombInit =
SemaRef.BuildBinOp(CurScope, InitLoc, BO_Assign, IV.get(), CombRHS);
CombInit = SemaRef.ActOnFinishFullExpr(CombInit.get());
CombInit =
SemaRef.ActOnFinishFullExpr(CombInit.get(), /*DiscardedValue*/ false);
}
}
@ -5426,7 +5428,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
if (!Inc.isUsable())
return 0;
Inc = SemaRef.BuildBinOp(CurScope, IncLoc, BO_Assign, IV.get(), Inc.get());
Inc = SemaRef.ActOnFinishFullExpr(Inc.get());
Inc = SemaRef.ActOnFinishFullExpr(Inc.get(), /*DiscardedValue*/ false);
if (!Inc.isUsable())
return 0;
@ -5444,7 +5446,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
// LB = LB + ST
NextLB =
SemaRef.BuildBinOp(CurScope, IncLoc, BO_Assign, LB.get(), NextLB.get());
NextLB = SemaRef.ActOnFinishFullExpr(NextLB.get());
NextLB =
SemaRef.ActOnFinishFullExpr(NextLB.get(), /*DiscardedValue*/ false);
if (!NextLB.isUsable())
return 0;
// UB + ST
@ -5454,7 +5457,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
// UB = UB + ST
NextUB =
SemaRef.BuildBinOp(CurScope, IncLoc, BO_Assign, UB.get(), NextUB.get());
NextUB = SemaRef.ActOnFinishFullExpr(NextUB.get());
NextUB =
SemaRef.ActOnFinishFullExpr(NextUB.get(), /*DiscardedValue*/ false);
if (!NextUB.isUsable())
return 0;
if (isOpenMPLoopBoundSharingDirective(DKind)) {
@ -5465,7 +5469,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
// LB = LB + ST
CombNextLB = SemaRef.BuildBinOp(CurScope, IncLoc, BO_Assign, CombLB.get(),
CombNextLB.get());
CombNextLB = SemaRef.ActOnFinishFullExpr(CombNextLB.get());
CombNextLB = SemaRef.ActOnFinishFullExpr(CombNextLB.get(),
/*DiscardedValue*/ false);
if (!CombNextLB.isUsable())
return 0;
// UB + ST
@ -5476,7 +5481,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
// UB = UB + ST
CombNextUB = SemaRef.BuildBinOp(CurScope, IncLoc, BO_Assign, CombUB.get(),
CombNextUB.get());
CombNextUB = SemaRef.ActOnFinishFullExpr(CombNextUB.get());
CombNextUB = SemaRef.ActOnFinishFullExpr(CombNextUB.get(),
/*DiscardedValue*/ false);
if (!CombNextUB.isUsable())
return 0;
}
@ -5497,7 +5503,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
assert(DistInc.isUsable() && "distribute inc expr was not built");
DistInc = SemaRef.BuildBinOp(CurScope, DistIncLoc, BO_Assign, IV.get(),
DistInc.get());
DistInc = SemaRef.ActOnFinishFullExpr(DistInc.get());
DistInc =
SemaRef.ActOnFinishFullExpr(DistInc.get(), /*DiscardedValue*/ false);
assert(DistInc.isUsable() && "distribute inc expr was not built");
// Build expression: UB = min(UB, prevUB) for #for in composite or combined
@ -5509,7 +5516,8 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
DistEUBLoc, DistEUBLoc, IsUBGreater.get(), PrevUB.get(), UB.get());
PrevEUB = SemaRef.BuildBinOp(CurScope, DistIncLoc, BO_Assign, UB.get(),
CondOp.get());
PrevEUB = SemaRef.ActOnFinishFullExpr(PrevEUB.get());
PrevEUB =
SemaRef.ActOnFinishFullExpr(PrevEUB.get(), /*DiscardedValue*/ false);
// Build IV <= PrevUB to be used in parallel for is in combination with
// a distribute directive with schedule(static, 1)
@ -5613,8 +5621,10 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
Built.IterationVarRef = IV.get();
Built.LastIteration = LastIteration.get();
Built.NumIterations = NumIterations.get();
Built.CalcLastIteration =
SemaRef.ActOnFinishFullExpr(CalcLastIteration.get()).get();
Built.CalcLastIteration = SemaRef
.ActOnFinishFullExpr(CalcLastIteration.get(),
/*DiscardedValue*/ false)
.get();
Built.PreCond = PreCond.get();
Built.PreInits = buildPreInits(C, Captures);
Built.Cond = Cond.get();
@ -10267,8 +10277,8 @@ OMPClause *Sema::ActOnOpenMPLastprivateClause(ArrayRef<Expr *> VarList,
PseudoDstExpr, PseudoSrcExpr);
if (AssignmentOp.isInvalid())
continue;
AssignmentOp = ActOnFinishFullExpr(AssignmentOp.get(), ELoc,
/*DiscardedValue=*/true);
AssignmentOp =
ActOnFinishFullExpr(AssignmentOp.get(), ELoc, /*DiscardedValue*/ false);
if (AssignmentOp.isInvalid())
continue;
@ -11274,7 +11284,8 @@ static bool actOnOMPReductionKindClause(
BO_Assign, LHSDRE, ConditionalOp);
}
if (ReductionOp.isUsable())
ReductionOp = S.ActOnFinishFullExpr(ReductionOp.get());
ReductionOp = S.ActOnFinishFullExpr(ReductionOp.get(),
/*DiscardedValue*/ false);
}
if (!ReductionOp.isUsable())
continue;
@ -11612,7 +11623,7 @@ OMPClause *Sema::ActOnOpenMPLinearClause(
buildDeclRefExpr(*this, SaveVar, StepExpr->getType(), StepLoc);
ExprResult CalcStep =
BuildBinOp(CurScope, StepLoc, BO_Assign, SaveRef.get(), StepExpr);
CalcStep = ActOnFinishFullExpr(CalcStep.get());
CalcStep = ActOnFinishFullExpr(CalcStep.get(), /*DiscardedValue*/ false);
// Warn about zero linear step (it would be probably better specified as
// making corresponding variables 'const').
@ -11700,7 +11711,7 @@ static bool FinishOpenMPLinearClause(OMPLinearClause &Clause, DeclRefExpr *IV,
else
Update = *CurPrivate;
Update = SemaRef.ActOnFinishFullExpr(Update.get(), DE->getBeginLoc(),
/*DiscardedValue=*/true);
/*DiscardedValue*/ false);
// Build final: Var = InitExpr + NumIterations * Step
ExprResult Final;
@ -11711,7 +11722,7 @@ static bool FinishOpenMPLinearClause(OMPLinearClause &Clause, DeclRefExpr *IV,
else
Final = *CurPrivate;
Final = SemaRef.ActOnFinishFullExpr(Final.get(), DE->getBeginLoc(),
/*DiscardedValue=*/true);
/*DiscardedValue*/ false);
if (!Update.isUsable() || !Final.isUsable()) {
Updates.push_back(nullptr);
@ -11879,7 +11890,7 @@ OMPClause *Sema::ActOnOpenMPCopyinClause(ArrayRef<Expr *> VarList,
if (AssignmentOp.isInvalid())
continue;
AssignmentOp = ActOnFinishFullExpr(AssignmentOp.get(), DE->getExprLoc(),
/*DiscardedValue=*/true);
/*DiscardedValue*/ false);
if (AssignmentOp.isInvalid())
continue;
@ -11987,8 +11998,8 @@ OMPClause *Sema::ActOnOpenMPCopyprivateClause(ArrayRef<Expr *> VarList,
DSAStack->getCurScope(), ELoc, BO_Assign, PseudoDstExpr, PseudoSrcExpr);
if (AssignmentOp.isInvalid())
continue;
AssignmentOp = ActOnFinishFullExpr(AssignmentOp.get(), ELoc,
/*DiscardedValue=*/true);
AssignmentOp =
ActOnFinishFullExpr(AssignmentOp.get(), ELoc, /*DiscardedValue*/ false);
if (AssignmentOp.isInvalid())
continue;

65
clang/lib/Sema/SemaStmt.cpp
View File

@ -42,12 +42,11 @@
using namespace clang;
using namespace sema;
StmtResult Sema::ActOnExprStmt(ExprResult FE) {
StmtResult Sema::ActOnExprStmt(ExprResult FE, bool DiscardedValue) {
if (FE.isInvalid())
return StmtError();
FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(),
/*DiscardedValue*/ true);
FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(), DiscardedValue);
if (FE.isInvalid())
return StmtError();
@ -348,6 +347,10 @@ sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
return getCurFunction()->CompoundScopes.back();
}
bool Sema::isCurCompoundStmtAStmtExpr() const {
return getCurCompoundScope().IsStmtExpr;
}
StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
ArrayRef<Stmt *> Elts, bool isStmtExpr) {
const unsigned NumElts = Elts.size();
@ -370,14 +373,6 @@ StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
Diag(D->getLocation(), diag::ext_mixed_decls_code);
}
}
// Warn about unused expressions in statements.
for (unsigned i = 0; i != NumElts; ++i) {
// Ignore statements that are last in a statement expression.
if (isStmtExpr && i == NumElts - 1)
continue;
DiagnoseUnusedExprResult(Elts[i]);
}
// Check for suspicious empty body (null statement) in `for' and `while'
// statements. Don't do anything for template instantiations, this just adds
@ -469,15 +464,12 @@ Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal,
/// ActOnCaseStmtBody - This installs a statement as the body of a case.
void Sema::ActOnCaseStmtBody(Stmt *S, Stmt *SubStmt) {
DiagnoseUnusedExprResult(SubStmt);
cast<CaseStmt>(S)->setSubStmt(SubStmt);
}
StmtResult
Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
Stmt *SubStmt, Scope *CurScope) {
DiagnoseUnusedExprResult(SubStmt);
if (getCurFunction()->SwitchStack.empty()) {
Diag(DefaultLoc, diag::err_default_not_in_switch);
return SubStmt;
@ -571,9 +563,6 @@ StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
if (IsConstexpr || isa<ObjCAvailabilityCheckExpr>(Cond.get().second))
setFunctionHasBranchProtectedScope();
DiagnoseUnusedExprResult(thenStmt);
DiagnoseUnusedExprResult(elseStmt);
return IfStmt::Create(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
Cond.get().second, thenStmt, ElseLoc, elseStmt);
}
@ -1301,8 +1290,6 @@ StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc, ConditionResult Cond,
!Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
CommaVisitor(*this).Visit(CondVal.second);
DiagnoseUnusedExprResult(Body);
if (isa<NullStmt>(Body))
getCurCompoundScope().setHasEmptyLoopBodies();
@ -1322,7 +1309,7 @@ Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
return StmtError();
Cond = CondResult.get();
CondResult = ActOnFinishFullExpr(Cond, DoLoc);
CondResult = ActOnFinishFullExpr(Cond, DoLoc, /*DiscardedValue*/ false);
if (CondResult.isInvalid())
return StmtError();
Cond = CondResult.get();
@ -1332,8 +1319,6 @@ Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
!Diags.isIgnored(diag::warn_comma_operator, Cond->getExprLoc()))
CommaVisitor(*this).Visit(Cond);
DiagnoseUnusedExprResult(Body);
return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
}
@ -1778,11 +1763,6 @@ StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
CommaVisitor(*this).Visit(Second.get().second);
Expr *Third = third.release().getAs<Expr>();
DiagnoseUnusedExprResult(First);
DiagnoseUnusedExprResult(Third);
DiagnoseUnusedExprResult(Body);
if (isa<NullStmt>(Body))
getCurCompoundScope().setHasEmptyLoopBodies();
@ -1802,7 +1782,7 @@ StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
if (result.isInvalid()) return StmtError();
E = result.get();
ExprResult FullExpr = ActOnFinishFullExpr(E);
ExprResult FullExpr = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
if (FullExpr.isInvalid())
return StmtError();
return StmtResult(static_cast<Stmt*>(FullExpr.get()));
@ -1956,7 +1936,8 @@ Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
if (CollectionExprResult.isInvalid())
return StmtError();
CollectionExprResult = ActOnFinishFullExpr(CollectionExprResult.get());
CollectionExprResult =
ActOnFinishFullExpr(CollectionExprResult.get(), /*DiscardedValue*/ false);
if (CollectionExprResult.isInvalid())
return StmtError();
@ -2593,7 +2574,8 @@ StmtResult Sema::BuildCXXForRangeStmt(SourceLocation ForLoc,
if (!NotEqExpr.isInvalid())
NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
if (!NotEqExpr.isInvalid())
NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
NotEqExpr =
ActOnFinishFullExpr(NotEqExpr.get(), /*DiscardedValue*/ false);
if (NotEqExpr.isInvalid()) {
Diag(RangeLoc, diag::note_for_range_invalid_iterator)
<< RangeLoc << 0 << BeginRangeRef.get()->getType();
@ -2616,7 +2598,7 @@ StmtResult Sema::BuildCXXForRangeStmt(SourceLocation ForLoc,
// co_await during the initial parse.
IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
if (!IncrExpr.isInvalid())
IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
IncrExpr = ActOnFinishFullExpr(IncrExpr.get(), /*DiscardedValue*/ false);
if (IncrExpr.isInvalid()) {
Diag(RangeLoc, diag::note_for_range_invalid_iterator)
<< RangeLoc << 2 << BeginRangeRef.get()->getType() ;
@ -2871,7 +2853,7 @@ Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
return StmtError();
}
ExprResult ExprRes = ActOnFinishFullExpr(E);
ExprResult ExprRes = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
if (ExprRes.isInvalid())
return StmtError();
E = ExprRes.get();
@ -3221,7 +3203,8 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
ExpressionEvaluationContext::DiscardedStatement &&
(HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
if (RetValExp) {
ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
ExprResult ER =
ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
if (ER.isInvalid())
return StmtError();
RetValExp = ER.get();
@ -3348,7 +3331,8 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
}
if (RetValExp) {
ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
ExprResult ER =
ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
if (ER.isInvalid())
return StmtError();
RetValExp = ER.get();
@ -3578,7 +3562,8 @@ StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
ExpressionEvaluationContext::DiscardedStatement &&
FnRetType->getContainedAutoType()) {
if (RetValExp) {
ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
ExprResult ER =
ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
if (ER.isInvalid())
return StmtError();
RetValExp = ER.get();
@ -3672,7 +3657,8 @@ StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
}
if (RetValExp) {
ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
ExprResult ER =
ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
if (ER.isInvalid())
return StmtError();
RetValExp = ER.get();
@ -3751,7 +3737,8 @@ StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
}
if (RetValExp) {
ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
ExprResult ER =
ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
if (ER.isInvalid())
return StmtError();
RetValExp = ER.get();
@ -3804,7 +3791,7 @@ StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
if (Result.isInvalid())
return StmtError();
Result = ActOnFinishFullExpr(Result.get());
Result = ActOnFinishFullExpr(Result.get(), /*DiscardedValue*/ false);
if (Result.isInvalid())
return StmtError();
Throw = Result.get();
@ -3876,7 +3863,7 @@ Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
}
// The operand to @synchronized is a full-expression.
return ActOnFinishFullExpr(operand);
return ActOnFinishFullExpr(operand, /*DiscardedValue*/ false);
}
StmtResult

15
clang/lib/Sema/TreeTransform.h
View File

@ -328,7 +328,7 @@ public:
/// other mechanism.
///
/// \returns the transformed statement.
StmtResult TransformStmt(Stmt *S);
StmtResult TransformStmt(Stmt *S, bool DiscardedValue = false);
/// Transform the given statement.
///
@ -3269,8 +3269,8 @@ private:
bool DeducibleTSTContext);
};
template<typename Derived>
StmtResult TreeTransform<Derived>::TransformStmt(Stmt *S) {
template <typename Derived>
StmtResult TreeTransform<Derived>::TransformStmt(Stmt *S, bool DiscardedValue) {
if (!S)
return S;
@ -3294,7 +3294,7 @@ StmtResult TreeTransform<Derived>::TransformStmt(Stmt *S) {
if (E.isInvalid())
return StmtError();
return getSema().ActOnExprStmt(E);
return getSema().ActOnExprStmt(E, DiscardedValue);
}
}
@ -4715,7 +4715,8 @@ TreeTransform<Derived>::TransformVariableArrayType(TypeLocBuilder &TLB,
}
if (SizeResult.isInvalid())
return QualType();
SizeResult = SemaRef.ActOnFinishFullExpr(SizeResult.get());
SizeResult =
SemaRef.ActOnFinishFullExpr(SizeResult.get(), /*DiscardedValue*/ false);
if (SizeResult.isInvalid())
return QualType();
@ -6520,7 +6521,9 @@ TreeTransform<Derived>::TransformCompoundStmt(CompoundStmt *S,
bool SubStmtChanged = false;
SmallVector<Stmt*, 8> Statements;
for (auto *B : S->body()) {
StmtResult Result = getDerived().TransformStmt(B);
StmtResult Result =
getDerived().TransformStmt(B, !IsStmtExpr || B != S->body_back());
if (Result.isInvalid()) {
// Immediately fail if this was a DeclStmt, since it's very
// likely that this will cause problems for future statements.

9
clang/test/CXX/stmt.stmt/stmt.select/p3.cpp
View File

@ -1,5 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// RUN: %clang_cc1 -fsyntax-only -std=c++1z -Wc++14-compat -verify %s -DCPP17
// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify %s
// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -std=c++1z -Wc++14-compat -verify %s -DCPP17
int f();
@ -71,7 +71,6 @@ void whileInitStatement() {
// last loop above. It would be nice to remove this.
void whileInitStatement2() {
while (; false) {} // expected-error {{expected expression}}
// expected-warning@-1 {{expression result unused}}
// expected-error@-2 {{expected ';' after expression}}
// expected-error@-3 {{expected expression}}
// expected-error@-1 {{expected ';' after expression}}
// expected-error@-2 {{expected expression}}
}

2
clang/test/CodeCompletion/pragma-macro-token-caching.c
View File

@ -12,7 +12,7 @@ void completeParam(int param) {
void completeParamPragmaError(int param) {
Outer(__extension__({ _Pragma(2) })); // expected-error {{_Pragma takes a parenthesized string literal}}
param;
param; // expected-warning {{expression result unused}}
}
// RUN: %clang_cc1 -fsyntax-only -verify -code-completion-at=%s:16:1 %s | FileCheck %s

8
clang/test/Parser/cxx1z-init-statement.cpp
View File

@ -13,9 +13,9 @@ int f() {
if (T(n) = 0; n) {}
// init-statement expressions
if (T{f()}; f()) {}
if (T{f()}, g, h; f()) {} // expected-warning 2{{unused}}
if (T(f()), g, h + 1; f()) {} // expected-warning 2{{unused}}
if (T{f()}; f()) {} // expected-warning {{expression result unused}}
if (T{f()}, g, h; f()) {} // expected-warning 2{{unused}} expected-warning {{expression result unused}}
if (T(f()), g, h + 1; f()) {} // expected-warning 2{{unused}} expected-warning {{expression result unused}}
// condition declarations
if (T(n){g}) {}
@ -35,7 +35,7 @@ int f() {
// Likewise for 'switch'
switch (int n; n) {}
switch (g; int g = 5) {}
switch (g; int g = 5) {} // expected-warning {{expression result unused}}
if (int a, b; int c = a) { // expected-note 6{{previous}}
int a; // expected-error {{redefinition}}

2
clang/test/Parser/switch-recovery.cpp
View File

@ -105,7 +105,7 @@ void test9(int x) { // expected-note {{'x' declared here}}
expected-error {{expected expression}}
8:: x; // expected-error {{expected ';' after expression}} \
expected-error {{no member named 'x' in the global namespace; did you mean simply 'x'?}} \
expected-warning 2 {{expression result unused}}
expected-warning {{expression result unused}}
9:: :y; // expected-error {{expected ';' after expression}} \
expected-error {{expected unqualified-id}} \
expected-warning {{expression result unused}}

8
clang/test/SemaCXX/cxx1z-init-statement.cpp
View File

@ -1,5 +1,5 @@
// RUN: %clang_cc1 -std=c++1z -verify %s
// RUN: %clang_cc1 -std=c++17 -verify %s
// RUN: %clang_cc1 -std=c++1z -Wno-unused-value -verify %s
// RUN: %clang_cc1 -std=c++17 -Wno-unused-value -verify %s
void testIf() {
int x = 0;
@ -12,7 +12,7 @@ void testIf() {
int x = 0; // expected-error {{redefinition of 'x'}}
if (x; int a = 0) ++a;
if (x, +x; int a = 0) // expected-note 2 {{previous definition is here}} expected-warning {{unused}}
if (x, +x; int a = 0) // expected-note 2 {{previous definition is here}}
int a = 0; // expected-error {{redefinition of 'a'}}
else
int a = 0; // expected-error {{redefinition of 'a'}}
@ -48,7 +48,7 @@ void testSwitch() {
++a;
}
switch (x, +x; int a = 0) { // expected-note {{previous definition is here}} expected-warning {{unused}}
switch (x, +x; int a = 0) { // expected-note {{previous definition is here}}
case 0:
int a = 0; // expected-error {{redefinition of 'a'}} // expected-note {{previous definition is here}}
case 1:

2
clang/test/SemaCXX/for-range-examples.cpp
View File

@ -244,7 +244,7 @@ void foo ()
{
int b = 1, a[b];
a[0] = 0;
[&] { for (int c : a) 0; } ();
[&] { for (int c : a) 0; } (); // expected-warning {{expression result unused}}
}

40
clang/test/SemaCXX/warn-unused-result.cpp
View File

@ -33,6 +33,36 @@ void test() {
const S &s4 = g1();
}
void testSubstmts(int i) {
switch (i) {
case 0:
f(); // expected-warning {{ignoring return value}}
default:
f(); // expected-warning {{ignoring return value}}
}
if (i)
f(); // expected-warning {{ignoring return value}}
else
f(); // expected-warning {{ignoring return value}}
while (i)
f(); // expected-warning {{ignoring return value}}
do
f(); // expected-warning {{ignoring return value}}
while (i);
for (f(); // expected-warning {{ignoring return value}}
;
f() // expected-warning {{ignoring return value}}
)
f(); // expected-warning {{ignoring return value}}
f(), // expected-warning {{ignoring return value}}
(void)f();
}
struct X {
int foo() __attribute__((warn_unused_result));
};
@ -206,3 +236,13 @@ void f() {
(void)++p;
}
} // namespace
namespace PR39837 {
[[clang::warn_unused_result]] int f(int);
void g() {
int a[2];
for (int b : a)
f(b); // expected-warning {{ignoring return value}}
}
} // namespace PR39837