[clang] cb08f4a - Support warn_unused_result on typedefs
David Blaikie via cfe-commits
cfe-commits at lists.llvm.org
Thu Jun 2 13:57:40 PDT 2022
Author: David Blaikie
Date: 2022-06-02T20:57:31Z
New Revision: cb08f4aa4467cf562b62e542725f5351c5482495
URL: https://github.com/llvm/llvm-project/commit/cb08f4aa4467cf562b62e542725f5351c5482495
DIFF: https://github.com/llvm/llvm-project/commit/cb08f4aa4467cf562b62e542725f5351c5482495.diff
LOG: Support warn_unused_result on typedefs
While it's not as robust as using the attribute on enums/classes (the
type information may be lost through a function pointer, a declaration
or use of the underlying type without using the typedef, etc) but I
think there's still value in being able to attribute a typedef and have
all return types written with that typedef pick up the
warn_unused_result behavior.
Specifically I'd like to be able to annotate LLVMErrorRef (a wrapper for
llvm::Error used in the C API - the underlying type is a raw pointer, so
it can't be attributed itself) to reduce the chance of unhandled errors.
Differential Revision: https://reviews.llvm.org/D102122
Added:
Modified:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttributeCommonInfo.h
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/AST/Expr.cpp
clang/lib/Basic/Attributes.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
clang/test/Misc/pragma-attribute-supported-attributes-list.test
clang/test/Sema/c2x-nodiscard.c
clang/test/Sema/unused-expr.c
clang/test/SemaCXX/warn-unused-result.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index fed29b03a8b14..4644323501272 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2944,7 +2944,7 @@ def WarnUnusedResult : InheritableAttr {
C2x<"", "nodiscard", 201904>,
CXX11<"clang", "warn_unused_result">,
GCC<"warn_unused_result">];
- let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike]>;
+ let Subjects = SubjectList<[ObjCMethod, Enum, Record, FunctionLike, TypedefName]>;
let Args = [StringArgument<"Message", 1>];
let Documentation = [WarnUnusedResultsDocs];
let AdditionalMembers = [{
diff --git a/clang/include/clang/Basic/AttributeCommonInfo.h b/clang/include/clang/Basic/AttributeCommonInfo.h
index 9eff0966e458a..afa8a893e921a 100644
--- a/clang/include/clang/Basic/AttributeCommonInfo.h
+++ b/clang/include/clang/Basic/AttributeCommonInfo.h
@@ -146,6 +146,7 @@ class AttributeCommonInfo {
bool isMicrosoftAttribute() const { return SyntaxUsed == AS_Microsoft; }
bool isGNUScope() const;
+ bool isClangScope() const;
bool isAlignasAttribute() const {
// FIXME: Use a better mechanism to determine this.
@@ -164,6 +165,8 @@ class AttributeCommonInfo {
return isCXX11Attribute() || isC2xAttribute();
}
+ bool isGNUAttribute() const { return SyntaxUsed == AS_GNU; }
+
bool isKeywordAttribute() const {
return SyntaxUsed == AS_Keyword || SyntaxUsed == AS_ContextSensitiveKeyword;
}
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 469f79a867524..0e6573241b55e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8734,6 +8734,10 @@ def warn_unused_result : Warning<
def warn_unused_result_msg : Warning<
"ignoring return value of function declared with %0 attribute: %1">,
InGroup<UnusedResult>;
+def warn_unused_result_typedef_unsupported_spelling : Warning<
+ "'[[%select{nodiscard|gnu::warn_unused_result}0]]' attribute ignored when "
+ "applied to a typedef; consider using '__attribute__((warn_unused_result))' "
+ "or '[[clang::warn_unused_result]]' instead">, InGroup<IgnoredAttributes>;
def warn_unused_volatile : Warning<
"expression result unused; assign into a variable to force a volatile load">,
InGroup<DiagGroup<"unused-volatile-lvalue">>;
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index c3dfae5cba061..79d092acccec9 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1522,6 +1522,11 @@ const Attr *CallExpr::getUnusedResultAttr(const ASTContext &Ctx) const {
if (const auto *A = TD->getAttr<WarnUnusedResultAttr>())
return A;
+ for (const auto *TD = getCallReturnType(Ctx)->getAs<TypedefType>(); TD;
+ TD = TD->desugar()->getAs<TypedefType>())
+ if (const auto *A = TD->getDecl()->getAttr<WarnUnusedResultAttr>())
+ return A;
+
// Otherwise, see if the callee is marked nodiscard and return that attribute
// instead.
const Decl *D = getCalleeDecl();
diff --git a/clang/lib/Basic/Attributes.cpp b/clang/lib/Basic/Attributes.cpp
index 62eea9c590825..bd27dc13a92f0 100644
--- a/clang/lib/Basic/Attributes.cpp
+++ b/clang/lib/Basic/Attributes.cpp
@@ -85,6 +85,10 @@ bool AttributeCommonInfo::isGNUScope() const {
return ScopeName && (ScopeName->isStr("gnu") || ScopeName->isStr("__gnu__"));
}
+bool AttributeCommonInfo::isClangScope() const {
+ return ScopeName && (ScopeName->isStr("clang") || ScopeName->isStr("_Clang"));
+}
+
#include "clang/Sema/AttrParsedAttrKinds.inc"
static SmallString<64> normalizeName(const IdentifierInfo *Name,
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index f39e1af10e3d7..466ca1b573be3 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3156,6 +3156,14 @@ static void handleWarnUnusedResult(Sema &S, Decl *D, const ParsedAttr &AL) {
S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL;
}
+ if ((!AL.isGNUAttribute() &&
+ !(AL.isStandardAttributeSyntax() && AL.isClangScope())) &&
+ isa<TypedefNameDecl>(D)) {
+ S.Diag(AL.getLoc(), diag::warn_unused_result_typedef_unsupported_spelling)
+ << AL.isGNUScope();
+ return;
+ }
+
D->addAttr(::new (S.Context) WarnUnusedResultAttr(S.Context, AL, Str));
}
diff --git a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
index 142d4d6f369f6..afa7869da5f43 100644
--- a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.nodiscard/p1.cpp
@@ -7,4 +7,4 @@ struct [[nodiscard("Wrong")]] S3 {};
[[nodiscard]] int f();
enum [[nodiscard]] E {};
-namespace [[nodiscard]] N {} // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+namespace [[nodiscard]] N {} // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 0713252385885..b9499229c0666 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -185,7 +185,7 @@
// CHECK-NEXT: VecReturn (SubjectMatchRule_record)
// CHECK-NEXT: VecTypeHint (SubjectMatchRule_function)
// CHECK-NEXT: WarnUnused (SubjectMatchRule_record)
-// CHECK-NEXT: WarnUnusedResult (SubjectMatchRule_objc_method, SubjectMatchRule_enum, SubjectMatchRule_record, SubjectMatchRule_hasType_functionType)
+// CHECK-NEXT: WarnUnusedResult (SubjectMatchRule_objc_method, SubjectMatchRule_enum, SubjectMatchRule_record, SubjectMatchRule_hasType_functionType, SubjectMatchRule_type_alias)
// CHECK-NEXT: Weak (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record)
// CHECK-NEXT: WeakRef (SubjectMatchRule_variable, SubjectMatchRule_function)
// CHECK-NEXT: WebAssemblyExportName (SubjectMatchRule_function)
diff --git a/clang/test/Sema/c2x-nodiscard.c b/clang/test/Sema/c2x-nodiscard.c
index fb38e20d8d7aa..77b81a523833c 100644
--- a/clang/test/Sema/c2x-nodiscard.c
+++ b/clang/test/Sema/c2x-nodiscard.c
@@ -15,7 +15,7 @@ struct S3 get_s3(void);
[[nodiscard]] int f1(void);
enum [[nodiscard]] E1 { One };
-[[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+[[nodiscard]] int i; // expected-warning {{'nodiscard' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
struct [[nodiscard]] S4 {
int i;
diff --git a/clang/test/Sema/unused-expr.c b/clang/test/Sema/unused-expr.c
index af4f0f39b8e5f..91923af371653 100644
--- a/clang/test/Sema/unused-expr.c
+++ b/clang/test/Sema/unused-expr.c
@@ -96,7 +96,7 @@ int t6(void) {
return 0;
}
-int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
+int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, function pointers, and typedefs}}
// PR4010
int (*fn4)(void) __attribute__ ((warn_unused_result));
diff --git a/clang/test/SemaCXX/warn-unused-result.cpp b/clang/test/SemaCXX/warn-unused-result.cpp
index d0bb4c9317dd2..4b7a2503ecc0d 100644
--- a/clang/test/SemaCXX/warn-unused-result.cpp
+++ b/clang/test/SemaCXX/warn-unused-result.cpp
@@ -254,3 +254,35 @@ __attribute__((warn_unused_result)) bool (*h)();
void i([[nodiscard]] bool (*fp)()); // expected-warning {{'nodiscard' attribute only applies to functions, classes, or enumerations}}
}
+
+namespace unused_typedef_result {
+[[clang::warn_unused_result]] typedef void *a;
+typedef a indirect;
+a af1();
+indirect indirectf1();
+void af2() {
+ af1(); // expected-warning {{ignoring return value}}
+ void *(*a1)();
+ a1(); // no warning
+ a (*a2)();
+ a2(); // expected-warning {{ignoring return value}}
+ indirectf1(); // expected-warning {{ignoring return value}}
+}
+[[nodiscard]] typedef void *b1; // expected-warning {{'[[nodiscard]]' attribute ignored when applied to a typedef; consider using '__attribute__((warn_unused_result))' or '[[clang::warn_unused_result]]' instead}}
+[[gnu::warn_unused_result]] typedef void *b2; // expected-warning {{'[[gnu::warn_unused_result]]' attribute ignored when applied to a typedef; consider using '__attribute__((warn_unused_result))' or '[[clang::warn_unused_result]]' instead}}
+b1 b1f1();
+b2 b2f1();
+void bf2() {
+ b1f1(); // no warning
+ b2f1(); // no warning
+}
+__attribute__((warn_unused_result)) typedef void *c;
+c cf1();
+void cf2() {
+ cf1(); // expected-warning {{ignoring return value}}
+ void *(*c1)();
+ c1();
+ c (*c2)();
+ c2(); // expected-warning {{ignoring return value}}
+}
+}
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