r350404 - Refactor the way we handle diagnosing unused expression results.
Aaron Ballman via cfe-commits
cfe-commits at lists.llvm.org
Sat Jan 5 07:15:37 PST 2019
On Fri, Jan 4, 2019 at 8:41 PM Richard Smith <richard at metafoo.co.uk> wrote:
>
> On Fri, 4 Jan 2019 at 17:33, Nico Weber via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>>
>> Nice, this is finding bugs: https://bugs.chromium.org/p/chromium/issues/detail?id=919262
>>
>> However, I noticed that for that case, the same warning is printed twice:
>>
>> ../../third_party/crashpad/crashpad/util/win/process_info.cc(227,36): error: expression result unused [-Werror,-Wunused-value]
>> NTSTATUS_LOG(ERROR, status), "NtQueryInformationProcess";
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ../../third_party/crashpad/crashpad/util/win/process_info.cc(227,36): error: expression result unused [-Werror,-Wunused-value]
>> NTSTATUS_LOG(ERROR, status), "NtQueryInformationProcess";
>>
>>
>> Is that expected?
Yes and no. It's not unexpected, but it's not super helpful either. As
Richard points out below, this happens because of template
instantiation.
> The first diagnostic appears when parsing the template, the second one appears when instantiating it. In the complete diagnostic output:
>
> ../../third_party/crashpad/crashpad/util/win/process_info.cc(227,36): error: expression result unused [-Werror,-Wunused-value]
> NTSTATUS_LOG(ERROR, status), "NtQueryInformationProcess";
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> ../../third_party/crashpad/crashpad/util/win/process_info.cc(227,36): error: expression result unused [-Werror,-Wunused-value]
> NTSTATUS_LOG(ERROR, status), "NtQueryInformationProcess";
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../../third_party/crashpad/crashpad/util/win/process_info.cc(531,17): note: in instantiation of function template specialization 'crashpad::GetProcessBasicInformation<crashpad::process_types::internal::Traits32>' requested here
> bool result = GetProcessBasicInformation<process_types::internal::Traits32>(
> ^
>
> It'd be nice to suppress the diagnostic during instantiation if it appeared during the initial parse (generally, not with something specific to this warning).
Agreed, though I don't have the time to work on that currently.
Hopefully the behavior here isn't too onerous for Chromium (or other
projects)?
~Aaron
>
>> Code is here:
>> https://cs.chromium.org/chromium/src/third_party/crashpad/crashpad/util/win/process_info.cc?q=crashpad/util/win/process_info.cc&sq=package:chromium&g=0&l=227
>> https://cs.chromium.org/chromium/src/third_party/crashpad/crashpad/util/win/ntstatus_logging.h?type=cs&q=NTSTATUS_LOG&sq=package:chromium&g=0&l=63
>>
>>
>> On Fri, Jan 4, 2019 at 12:01 PM Aaron Ballman via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>>>
>>> Author: aaronballman
>>> Date: Fri Jan 4 08:58:14 2019
>>> New Revision: 350404
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=350404&view=rev
>>> Log:
>>> Refactor the way we handle diagnosing unused expression results.
>>>
>>> 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.
>>>
>>> Modified:
>>> cfe/trunk/include/clang/Parse/Parser.h
>>> cfe/trunk/include/clang/Sema/Sema.h
>>> cfe/trunk/lib/Parse/ParseObjc.cpp
>>> cfe/trunk/lib/Parse/ParseOpenMP.cpp
>>> cfe/trunk/lib/Parse/ParseStmt.cpp
>>> cfe/trunk/lib/Sema/SemaCoroutine.cpp
>>> cfe/trunk/lib/Sema/SemaDecl.cpp
>>> cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>>> cfe/trunk/lib/Sema/SemaExpr.cpp
>>> cfe/trunk/lib/Sema/SemaExprCXX.cpp
>>> cfe/trunk/lib/Sema/SemaLambda.cpp
>>> cfe/trunk/lib/Sema/SemaOpenMP.cpp
>>> cfe/trunk/lib/Sema/SemaStmt.cpp
>>> cfe/trunk/lib/Sema/TreeTransform.h
>>> cfe/trunk/test/CXX/stmt.stmt/stmt.select/p3.cpp
>>> cfe/trunk/test/CodeCompletion/pragma-macro-token-caching.c
>>> cfe/trunk/test/Parser/cxx1z-init-statement.cpp
>>> cfe/trunk/test/Parser/switch-recovery.cpp
>>> cfe/trunk/test/SemaCXX/cxx1z-init-statement.cpp
>>> cfe/trunk/test/SemaCXX/for-range-examples.cpp
>>> cfe/trunk/test/SemaCXX/warn-unused-result.cpp
>>>
>>> Modified: cfe/trunk/include/clang/Parse/Parser.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Parse/Parser.h?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/Parse/Parser.h (original)
>>> +++ cfe/trunk/include/clang/Parse/Parser.h Fri Jan 4 08:58:14 2019
>>> @@ -360,6 +360,11 @@ class Parser : public CodeCompletionHand
>>> /// 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;
>>>
>>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>>> +++ cfe/trunk/include/clang/Sema/Sema.h Fri Jan 4 08:58:14 2019
>>> @@ -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.
>>>
>>> Modified: cfe/trunk/lib/Parse/ParseObjc.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseObjc.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Parse/ParseObjc.cpp (original)
>>> +++ cfe/trunk/lib/Parse/ParseObjc.cpp Fri Jan 4 08:58:14 2019
>>> @@ -2741,7 +2741,7 @@ StmtResult Parser::ParseObjCAtStatement(
>>>
>>> // 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) {
>>>
>>> Modified: cfe/trunk/lib/Parse/ParseOpenMP.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseOpenMP.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Parse/ParseOpenMP.cpp (original)
>>> +++ cfe/trunk/lib/Parse/ParseOpenMP.cpp Fri Jan 4 08:58:14 2019
>>> @@ -314,7 +314,7 @@ Parser::ParseOpenMPDeclareReductionDirec
>>> 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::ParseOpenMPDeclareReductionDirec
>>> if (Actions.getLangOpts().CPlusPlus) {
>>> InitializerResult = Actions.ActOnFinishFullExpr(
>>> ParseAssignmentExpression().get(), D->getLocation(),
>>> - /*DiscardedValue=*/true);
>>> + /*DiscardedValue*/ false);
>>> } else {
>>> ConsumeToken();
>>> ParseOpenMPReductionInitializerForDecl(OmpPrivParm);
>>> @@ -364,7 +364,7 @@ Parser::ParseOpenMPDeclareReductionDirec
>>> } 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
>>> 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::ParseOpenMPSingleExpr
>>> 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(OpenMPDi
>>> 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
>>>
>>> Modified: cfe/trunk/lib/Parse/ParseStmt.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseStmt.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Parse/ParseStmt.cpp (original)
>>> +++ cfe/trunk/lib/Parse/ParseStmt.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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
>>> 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::ParseCompoundStatemen
>>> // 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(Sou
>>> 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)) {
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaCoroutine.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCoroutine.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaCoroutine.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaCoroutine.cpp Fri Jan 4 08:58:14 2019
>>> @@ -647,7 +647,7 @@ bool Sema::ActOnCoroutineBodyStart(Scope
>>> 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(Sourc
>>> 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::makeNewAndDel
>>>
>>> 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::makeNewAndDel
>>>
>>> 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::makeOnExcepti
>>>
>>> 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::makeGroDeclAn
>>> "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::makeGroDeclAn
>>> if (Res.isInvalid())
>>> return false;
>>>
>>> - Res = S.ActOnFinishFullExpr(Res.get());
>>> + Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
>>> if (Res.isInvalid())
>>> return false;
>>>
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Fri Jan 4 08:58:14 2019
>>> @@ -11204,9 +11204,9 @@ void Sema::AddInitializerToDecl(Decl *Re
>>> // 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;
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Fri Jan 4 08:58:14 2019
>>> @@ -1205,7 +1205,7 @@ static bool checkTupleLikeDecomposition(
>>> 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::ActOnFinishCXXInClassMemberIn
>>> // 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 *
>>> // 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(TypeSou
>>> // 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 Base
>>> // 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;
>>>
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Fri Jan 4 08:58:14 2019
>>> @@ -4736,8 +4736,9 @@ bool Sema::CheckCXXDefaultArgExpr(Source
>>> 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;
>>>
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Fri Jan 4 08:58:14 2019
>>> @@ -7803,6 +7803,8 @@ ExprResult Sema::ActOnFinishFullExpr(Exp
>>> FullExpr = IgnoredValueConversions(FullExpr.get());
>>> if (FullExpr.isInvalid())
>>> return ExprError();
>>> +
>>> + DiagnoseUnusedExprResult(FullExpr.get());
>>> }
>>>
>>> FullExpr = CorrectDelayedTyposInExpr(FullExpr.get());
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaLambda.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLambda.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaLambda.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaLambda.cpp Fri Jan 4 08:58:14 2019
>>> @@ -1724,7 +1724,7 @@ ExprResult Sema::BuildBlockForLambdaConv
>>> /*NRVO=*/false),
>>> CurrentLocation, Src);
>>> if (!Init.isInvalid())
>>> - Init = ActOnFinishFullExpr(Init.get());
>>> + Init = ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
>>>
>>> if (Init.isInvalid())
>>> return ExprError();
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaOpenMP.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaOpenMP.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaOpenMP.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaOpenMP.cpp Fri Jan 4 08:58:14 2019
>>> @@ -5320,7 +5320,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKin
>>> 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 DKin
>>> 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 DKin
>>> ? 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 DKin
>>> : 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 DKin
>>> 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 DKin
>>> // 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 DKin
>>> // 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 DKin
>>> // 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 DKin
>>> // 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 DKin
>>> 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 DKin
>>> 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 DKin
>>> 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::ActOnOpenMPLastprivateC
>>> 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(OMP
>>> 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(OMP
>>> 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
>>> if (AssignmentOp.isInvalid())
>>> continue;
>>> AssignmentOp = ActOnFinishFullExpr(AssignmentOp.get(), DE->getExprLoc(),
>>> - /*DiscardedValue=*/true);
>>> + /*DiscardedValue*/ false);
>>> if (AssignmentOp.isInvalid())
>>> continue;
>>>
>>> @@ -11987,8 +11998,8 @@ OMPClause *Sema::ActOnOpenMPCopyprivateC
>>> 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;
>>>
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaStmt.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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::getCurCom
>>> 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(Sourc
>>> 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 CaseL
>>>
>>> /// 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(SourceLocat
>>> 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(SourceLo
>>> !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,
>>> 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,
>>> !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(SourceLoca
>>> 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(
>>> 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(SourceL
>>> 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(So
>>> 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(So
>>> // 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(SourceLocati
>>> 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(SourceLoca
>>> 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(SourceLoca
>>> }
>>>
>>> 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(SourceL
>>> 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(SourceL
>>> }
>>>
>>> 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(SourceL
>>> }
>>>
>>> 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(So
>>> 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(Sou
>>> }
>>>
>>> // The operand to @synchronized is a full-expression.
>>> - return ActOnFinishFullExpr(operand);
>>> + return ActOnFinishFullExpr(operand, /*DiscardedValue*/ false);
>>> }
>>>
>>> StmtResult
>>>
>>> Modified: cfe/trunk/lib/Sema/TreeTransform.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/TreeTransform.h?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/TreeTransform.h (original)
>>> +++ cfe/trunk/lib/Sema/TreeTransform.h Fri Jan 4 08:58:14 2019
>>> @@ -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>::Trans
>>> if (E.isInvalid())
>>> return StmtError();
>>>
>>> - return getSema().ActOnExprStmt(E);
>>> + return getSema().ActOnExprStmt(E, DiscardedValue);
>>> }
>>> }
>>>
>>> @@ -4715,7 +4715,8 @@ TreeTransform<Derived>::TransformVariabl
>>> }
>>> 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>::TransformCompoun
>>> 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.
>>>
>>> Modified: cfe/trunk/test/CXX/stmt.stmt/stmt.select/p3.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/stmt.stmt/stmt.select/p3.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/CXX/stmt.stmt/stmt.select/p3.cpp (original)
>>> +++ cfe/trunk/test/CXX/stmt.stmt/stmt.select/p3.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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 at -1 {{expression result unused}}
>>> - // expected-error at -2 {{expected ';' after expression}}
>>> - // expected-error at -3 {{expected expression}}
>>> + // expected-error at -1 {{expected ';' after expression}}
>>> + // expected-error at -2 {{expected expression}}
>>> }
>>>
>>> Modified: cfe/trunk/test/CodeCompletion/pragma-macro-token-caching.c
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeCompletion/pragma-macro-token-caching.c?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/CodeCompletion/pragma-macro-token-caching.c (original)
>>> +++ cfe/trunk/test/CodeCompletion/pragma-macro-token-caching.c Fri Jan 4 08:58:14 2019
>>> @@ -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
>>>
>>> Modified: cfe/trunk/test/Parser/cxx1z-init-statement.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/cxx1z-init-statement.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/Parser/cxx1z-init-statement.cpp (original)
>>> +++ cfe/trunk/test/Parser/cxx1z-init-statement.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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}}
>>>
>>> Modified: cfe/trunk/test/Parser/switch-recovery.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/switch-recovery.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/Parser/switch-recovery.cpp (original)
>>> +++ cfe/trunk/test/Parser/switch-recovery.cpp Fri Jan 4 08:58:14 2019
>>> @@ -105,7 +105,7 @@ void test9(int x) { // expected-note {{'
>>> 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}}
>>>
>>> Modified: cfe/trunk/test/SemaCXX/cxx1z-init-statement.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx1z-init-statement.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaCXX/cxx1z-init-statement.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/cxx1z-init-statement.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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:
>>>
>>> Modified: cfe/trunk/test/SemaCXX/for-range-examples.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/for-range-examples.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaCXX/for-range-examples.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/for-range-examples.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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}}
>>> }
>>>
>>>
>>>
>>> Modified: cfe/trunk/test/SemaCXX/warn-unused-result.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-unused-result.cpp?rev=350404&r1=350403&r2=350404&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaCXX/warn-unused-result.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/warn-unused-result.cpp Fri Jan 4 08:58:14 2019
>>> @@ -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
>>>
>>>
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