Author: aaronballman
Date: Tue Oct 17 13:33:35 2017
New Revision: 316026
URL: http://llvm.org/viewvc/llvm-project?rev=316026&view=rev
Log:
Enable support for the [[nodiscard]] attribute from WG14 N2050 when enabling
double square bracket attributes in C code.
Added:
cfe/trunk/test/Sema/c2x-nodiscard.c
Modified:
cfe/trunk/include/clang/Basic/Attr.td
cfe/trunk/lib/AST/Decl.cpp
Modified: cfe/trunk/include/clang/Basic/Attr.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=316026&r1=316025&r2=316026&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/Attr.td (original)
+++ cfe/trunk/include/clang/Basic/Attr.td Tue Oct 17 13:33:35 2017
@@ -2004,10 +2004,10 @@ def WarnUnused : InheritableAttr {
}
def WarnUnusedResult : InheritableAttr {
- let Spellings = [CXX11<"", "nodiscard", 201603>,
+ let Spellings = [CXX11<"", "nodiscard", 201603>, C2x<"", "nodiscard">,
CXX11<"clang", "warn_unused_result">,
GCC<"warn_unused_result">];
- let Subjects = SubjectList<[ObjCMethod, Enum, CXXRecord, FunctionLike],
+ let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike],
WarnDiag, "ExpectedFunctionMethodEnumOrClass">;
let Documentation = [WarnUnusedResultsDocs];
}
Modified: cfe/trunk/lib/AST/Decl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Decl.cpp?rev=316026&r1=316025&r2=316026&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Decl.cpp (original)
+++ cfe/trunk/lib/AST/Decl.cpp Tue Oct 17 13:33:35 2017
@@ -3056,7 +3056,8 @@ SourceRange FunctionDecl::getExceptionSp
const Attr *FunctionDecl::getUnusedResultAttr() const {
QualType RetType = getReturnType();
if (RetType->isRecordType()) {
- if (const CXXRecordDecl *Ret = RetType->getAsCXXRecordDecl()) {
+ if (const auto *Ret =
+ dyn_cast_or_null<RecordDecl>(RetType->getAsTagDecl())) {
if (const auto *R = Ret->getAttr<WarnUnusedResultAttr>())
return R;
}
Added: cfe/trunk/test/Sema/c2x-nodiscard.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/c2x-nodiscard.c?rev=316026&view=auto
==============================================================================
--- cfe/trunk/test/Sema/c2x-nodiscard.c (added)
+++ cfe/trunk/test/Sema/c2x-nodiscard.c Tue Oct 17 13:33:35 2017
@@ -0,0 +1,49 @@
+// RUN: %clang_cc1 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+
+struct [[nodiscard]] S1 { // ok
+ int i;
+};
+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}}
+ int i;
+};
+
+[[nodiscard]] int f1(void);
+enum [[nodiscard]] E1 { One };
+
+[[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies
to functions, methods, enums, and classes}}
+
+struct [[nodiscard]] S4 {
+ int i;
+};
+struct S4 get_s(void);
+
+enum [[nodiscard]] E2 { Two };
+enum E2 get_e(void);
+
+[[nodiscard]] int get_i();
+
+void f2(void) {
+ get_s(); // expected-warning {{ignoring return value of function declared
with 'nodiscard' attribute}}
+ 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_i();
+ (void)get_e();
+}
+
+struct [[nodiscard]] error_info{
+ int i;
+};
+
+struct error_info enable_missile_safety_mode(void);
+void launch_missiles(void);
+void test_missiles(void) {
+ enable_missile_safety_mode(); // expected-warning {{ignoring return value of
function declared with 'nodiscard'}}
+ launch_missiles();
+}
+
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