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Enable support for the [[nodiscard]] attribute from WG14 N2050 when enabling double square bracket attributes in C code. 

llvm-svn: 316026
This commit is contained in:
Aaron Ballman 2017-10-17 20:33:35 +00:00
parent 96d9b7f5e1
commit 35713eba56
3 changed files with 53 additions and 3 deletions
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4
clang/include/clang/Basic/Attr.td
View File

@ -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];
}

3
clang/lib/AST/Decl.cpp
View File

@ -3056,7 +3056,8 @@ SourceRange FunctionDecl::getExceptionSpecSourceRange() const {
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;
}

49
clang/test/Sema/c2x-nodiscard.c Normal file
View File

@ -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();
}