On Sat, 20 Jul 2019 at 09:55, Aaron Ballman via cfe-commits < cfe-commits@lists.llvm.org> wrote:
> Author: aaronballman > Date: Sat Jul 20 00:56:34 2019 > New Revision: 366626 > > URL: http://llvm.org/viewvc/llvm-project?rev=366626&view=rev > Log: > Implement P1301R4, which allows specifying an optional message on the > [[nodiscard]] attribute. > > This also bumps the attribute feature test value and introduces the notion > of a C++2a extension warning. > > Modified: > cfe/trunk/include/clang/Basic/Attr.td > cfe/trunk/include/clang/Basic/AttrDocs.td > cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td > cfe/trunk/lib/Sema/SemaDeclAttr.cpp > cfe/trunk/lib/Sema/SemaStmt.cpp > cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp > cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp > cfe/trunk/test/Preprocessor/has_attribute.cpp > cfe/trunk/test/Sema/c2x-nodiscard.c > cfe/trunk/test/SemaCXX/cxx11-attr-print.cpp > > Modified: cfe/trunk/include/clang/Basic/Attr.td > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/include/clang/Basic/Attr.td (original) > +++ cfe/trunk/include/clang/Basic/Attr.td Sat Jul 20 00:56:34 2019 > @@ -2335,10 +2335,11 @@ def WarnUnused : InheritableAttr { > } > > def WarnUnusedResult : InheritableAttr { > - let Spellings = [CXX11<"", "nodiscard", 201603>, C2x<"", "nodiscard">, > + let Spellings = [CXX11<"", "nodiscard", 201907>, C2x<"", "nodiscard">, > We shouldn't bump the version until we also implement P1771R1, as this number indicates that both papers are implemented. > CXX11<"clang", "warn_unused_result">, > GCC<"warn_unused_result">]; > let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike]>; > + let Args = [StringArgument<"Message", 1>]; > let Documentation = [WarnUnusedResultsDocs]; > } > > > Modified: cfe/trunk/include/clang/Basic/AttrDocs.td > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/AttrDocs.td?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/include/clang/Basic/AttrDocs.td (original) > +++ cfe/trunk/include/clang/Basic/AttrDocs.td Sat Jul 20 00:56:34 2019 > @@ -1482,6 +1482,13 @@ generated when a function or its return > potentially-evaluated discarded-value expression that is not explicitly > cast to > `void`. > > +A string literal may optionally be provided to the attribute, which will > be > +reproduced in any resulting diagnostics. Redeclarations using different > forms > +of the attribute (with or without the string literal or with different > string > +literal contents) are allowed. If there are redeclarations of the entity > with > +differing string literals, it is unspecified which one will be used by > Clang > +in any resulting diagnostics. > + > .. code-block: c++ > struct [[nodiscard]] error_info { /*...*/ }; > error_info enable_missile_safety_mode(); > > Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) > +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Sat Jul 20 > 00:56:34 2019 > @@ -7436,6 +7436,9 @@ def warn_side_effects_typeid : Warning< > def warn_unused_result : Warning< > "ignoring return value of function declared with %0 attribute">, > InGroup<UnusedResult>; > +def warn_unused_result_msg : Warning< > + "ignoring return value of function declared with %0 attribute: %1">, > + InGroup<UnusedResult>; > def warn_unused_volatile : Warning< > "expression result unused; assign into a variable to force a volatile > load">, > InGroup<DiagGroup<"unused-volatile-lvalue">>; > @@ -7444,6 +7447,8 @@ def ext_cxx14_attr : Extension< > "use of the %0 attribute is a C++14 extension">, InGroup<CXX14>; > def ext_cxx17_attr : Extension< > "use of the %0 attribute is a C++17 extension">, InGroup<CXX17>; > +def ext_cxx2a_attr : Extension< > + "use of the %0 attribute is a C++2a extension">, InGroup<CXX2a>; > > def warn_unused_comparison : Warning< > "%select{equality|inequality|relational|three-way}0 comparison result > unused">, > > Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original) > +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Sat Jul 20 00:56:34 2019 > @@ -2841,14 +2841,30 @@ static void handleWarnUnusedResult(Sema > return; > } > > - // If this is spelled as the standard C++17 attribute, but not in > C++17, warn > - // about using it as an extension. > - if (!S.getLangOpts().CPlusPlus17 && AL.isCXX11Attribute() && > - !AL.getScopeName()) > - S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL; > + StringRef Str; > + if ((AL.isCXX11Attribute() || AL.isC2xAttribute()) && > !AL.getScopeName()) { > + // If this is spelled as the standard C++17 attribute, but not in > C++17, > + // warn about using it as an extension. If there are attribute > arguments, > + // then claim it's a C++2a extension instead. > + // FIXME: If WG14 does not seem likely to adopt the same feature, add > an > + // extension warning for C2x mode. > + const LangOptions &LO = S.getLangOpts(); > + if (AL.getNumArgs() == 1) { > + if (LO.CPlusPlus && !LO.CPlusPlus2a) > + S.Diag(AL.getLoc(), diag::ext_cxx2a_attr) << AL; > + > + // Since this this is spelled [[nodiscard]], get the optional string > + // literal. If in C++ mode, but not in C++2a mode, diagnose as an > + // extension. > + // FIXME: C2x should support this feature as well, even as an > extension. > + if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, nullptr)) > + return; > + } else if (LO.CPlusPlus && !LO.CPlusPlus17) > + S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL; > + } > > D->addAttr(::new (S.Context) > - WarnUnusedResultAttr(AL.getRange(), S.Context, > + WarnUnusedResultAttr(AL.getRange(), S.Context, Str, > AL.getAttributeSpellingListIndex())); > } > > > Modified: cfe/trunk/lib/Sema/SemaStmt.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/lib/Sema/SemaStmt.cpp (original) > +++ cfe/trunk/lib/Sema/SemaStmt.cpp Sat Jul 20 00:56:34 2019 > @@ -258,8 +258,13 @@ void Sema::DiagnoseUnusedExprResult(cons > if (E->getType()->isVoidType()) > return; > > - if (const Attr *A = CE->getUnusedResultAttr(Context)) { > - Diag(Loc, diag::warn_unused_result) << A << R1 << R2; > + if (const auto *A = cast_or_null<WarnUnusedResultAttr>( > + CE->getUnusedResultAttr(Context))) { > + StringRef Msg = A->getMessage(); > + if (!Msg.empty()) > + Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2; > + else > + Diag(Loc, diag::warn_unused_result) << A << R1 << R2; > return; > } > > @@ -290,7 +295,11 @@ void Sema::DiagnoseUnusedExprResult(cons > const ObjCMethodDecl *MD = ME->getMethodDecl(); > if (MD) { > if (const auto *A = MD->getAttr<WarnUnusedResultAttr>()) { > - Diag(Loc, diag::warn_unused_result) << A << R1 << R2; > + StringRef Msg = A->getMessage(); > + if (!Msg.empty()) > + Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2; > + else > + Diag(Loc, diag::warn_unused_result) << A << R1 << R2; > return; > } > } > > Modified: cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp > (original) > +++ cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp Sat Jul > 20 00:56:34 2019 > @@ -1,8 +1,8 @@ > -// RUN: %clang_cc1 -fsyntax-only -std=c++1z -verify %s > +// RUN: %clang_cc1 -fsyntax-only -std=c++2a -verify %s > > struct [[nodiscard]] S1 {}; // ok > struct [[nodiscard nodiscard]] S2 {}; // expected-error {{attribute > 'nodiscard' cannot appear multiple times in an attribute specifier}} > -struct [[nodiscard("Wrong")]] S3 {}; // expected-error {{'nodiscard' > cannot have an argument list}} > +struct [[nodiscard("Wrong")]] S3 {}; > > [[nodiscard]] int f(); > enum [[nodiscard]] E {}; > > Modified: cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp > (original) > +++ cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p2.cpp Sat Jul > 20 00:56:34 2019 > @@ -1,5 +1,6 @@ > +// RUN: %clang_cc1 -fsyntax-only -std=c++2a -verify -Wc++2a-extensions %s > // RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify -Wc++17-extensions %s > -// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT > -Wc++17-extensions %s > +// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT > -Wc++17-extensions -Wc++2a-extensions %s > > struct [[nodiscard]] S {}; > S get_s(); > @@ -61,10 +62,33 @@ void f() { > } > } // namespace PR31526 > > +struct [[nodiscard("reason")]] ReasonStruct {}; > +struct LaterReason; > +struct [[nodiscard("later reason")]] LaterReason {}; > + > +ReasonStruct get_reason(); > +LaterReason get_later_reason(); > +[[nodiscard("another reason")]] int another_reason(); > + > +[[nodiscard("conflicting reason")]] int conflicting_reason(); > +[[nodiscard("special reason")]] int conflicting_reason(); > + > +void cxx2a_use() { > + get_reason(); // expected-warning {{ignoring return value of function > declared with 'nodiscard' attribute: reason}} > + get_later_reason(); // expected-warning {{ignoring return value of > function declared with 'nodiscard' attribute: later reason}} > + another_reason(); // expected-warning {{ignoring return value of > function declared with 'nodiscard' attribute: another reason}} > + conflicting_reason(); // expected-warning {{ignoring return value of > function declared with 'nodiscard' attribute: special reason}} > +} > + > #ifdef EXT > -// expected-warning@4 {{use of the 'nodiscard' attribute is a C++17 > extension}} > -// expected-warning@8 {{use of the 'nodiscard' attribute is a C++17 > extension}} > -// expected-warning@11 {{use of the 'nodiscard' attribute is a C++17 > extension}} > +// expected-warning@5 {{use of the 'nodiscard' attribute is a C++17 > extension}} > +// expected-warning@9 {{use of the 'nodiscard' attribute is a C++17 > extension}} > // expected-warning@12 {{use of the 'nodiscard' attribute is a C++17 > extension}} > -// expected-warning@28 {{use of the 'nodiscard' attribute is a C++17 > extension}} > +// expected-warning@13 {{use of the 'nodiscard' attribute is a C++17 > extension}} > +// expected-warning@29 {{use of the 'nodiscard' attribute is a C++17 > extension}} > +// expected-warning@65 {{use of the 'nodiscard' attribute is a C++2a > extension}} > +// expected-warning@67 {{use of the 'nodiscard' attribute is a C++2a > extension}} > +// expected-warning@71 {{use of the 'nodiscard' attribute is a C++2a > extension}} > +// expected-warning@73 {{use of the 'nodiscard' attribute is a C++2a > extension}} > +// expected-warning@74 {{use of the 'nodiscard' attribute is a C++2a > extension}} > #endif > > Modified: cfe/trunk/test/Preprocessor/has_attribute.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Preprocessor/has_attribute.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/test/Preprocessor/has_attribute.cpp (original) > +++ cfe/trunk/test/Preprocessor/has_attribute.cpp Sat Jul 20 00:56:34 2019 > @@ -63,7 +63,7 @@ CXX11(unlikely) > // CHECK: maybe_unused: 201603L > // ITANIUM: no_unique_address: 201803L > // WINDOWS: no_unique_address: 0 > -// CHECK: nodiscard: 201603L > +// CHECK: nodiscard: 201907L > // CHECK: noreturn: 200809L > // FIXME(201803L) CHECK: unlikely: 0 > > > Modified: cfe/trunk/test/Sema/c2x-nodiscard.c > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/c2x-nodiscard.c?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/test/Sema/c2x-nodiscard.c (original) > +++ cfe/trunk/test/Sema/c2x-nodiscard.c Sat Jul 20 00:56:34 2019 > @@ -6,10 +6,12 @@ struct [[nodiscard]] S1 { // ok > struct [[nodiscard nodiscard]] S2 { // expected-error {{attribute > 'nodiscard' cannot appear multiple times in an attribute specifier}} > int i; > }; > -struct [[nodiscard("Wrong")]] S3 { // expected-error {{'nodiscard' cannot > have an argument list}} > +struct [[nodiscard("Wrong")]] S3 { // FIXME: may need an extension > warning. > int i; > }; > > +struct S3 get_s3(void); > + > [[nodiscard]] int f1(void); > enum [[nodiscard]] E1 { One }; > > @@ -27,11 +29,13 @@ enum E2 get_e(void); > > void f2(void) { > get_s(); // expected-warning {{ignoring return value of function > declared with 'nodiscard' attribute}} > + get_s3(); // expected-warning {{ignoring return value of function > declared with 'nodiscard' attribute: Wrong}} > get_i(); // expected-warning {{ignoring return value of function > declared with 'nodiscard' attribute}} > get_e(); // expected-warning {{ignoring return value of function > declared with 'nodiscard' attribute}} > > // Okay, warnings are not encouraged > (void)get_s(); > + (void)get_s3(); > (void)get_i(); > (void)get_e(); > } > > Modified: cfe/trunk/test/SemaCXX/cxx11-attr-print.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx11-attr-print.cpp?rev=366626&r1=366625&r2=366626&view=diff > > ============================================================================== > --- cfe/trunk/test/SemaCXX/cxx11-attr-print.cpp (original) > +++ cfe/trunk/test/SemaCXX/cxx11-attr-print.cpp Sat Jul 20 00:56:34 2019 > @@ -37,13 +37,15 @@ void foo() __attribute__((const)); > // CHECK: void bar() __attribute__((__const)); > void bar() __attribute__((__const)); > > -// CHECK: int f1() __attribute__((warn_unused_result)); > +// FIXME: It's unfortunate that the string literal prints with the below > three > +// cases given that the string is only exposed via the [[nodiscard]] > spelling. > +// CHECK: int f1() __attribute__((warn_unused_result(""))); > int f1() __attribute__((warn_unused_result)); > > -// CHECK: {{\[}}[clang::warn_unused_result]]; > +// CHECK: {{\[}}[clang::warn_unused_result("")]]; > int f2 [[clang::warn_unused_result]] (); > > -// CHECK: {{\[}}[gnu::warn_unused_result]]; > +// CHECK: {{\[}}[gnu::warn_unused_result("")]]; > int f3 [[gnu::warn_unused_result]] (); > > // FIXME: ast-print need to print C++11 > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
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