[clang] 5ce5e98 - [Clang] Add warnings for CWG2521
Po-yao Chang via cfe-commits
cfe-commits at lists.llvm.org
Tue Jul 18 16:24:01 PDT 2023
Author: Po-yao Chang
Date: 2023-07-19T07:23:34+08:00
New Revision: 5ce5e983f82c802e44faa8ed42d605d70c045ba9
URL: https://github.com/llvm/llvm-project/commit/5ce5e983f82c802e44faa8ed42d605d70c045ba9
DIFF: https://github.com/llvm/llvm-project/commit/5ce5e983f82c802e44faa8ed42d605d70c045ba9.diff
LOG: [Clang] Add warnings for CWG2521
1. Teach -Wuser-defined-literals to warn on using double underscores in
literal suffix identifiers.
2. Add -Wdeprecated-literal-operator to warn about the use of the first
grammar production of literal-operator-id, which defaults to off for now.
Differential Revision: https://reviews.llvm.org/D152632
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/include/clang/Basic/IdentifierTable.h
clang/lib/Basic/IdentifierTable.cpp
clang/lib/Sema/SemaDeclCXX.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/test/CXX/drs/dr25xx.cpp
clang/www/cxx_dr_status.html
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cad10dd090263c..7d7c07f818e0fd 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -142,6 +142,22 @@ Resolutions to C++ Defect Reports
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- Implemented `DR2397 <https://wg21.link/CWG2397>`_ which allows ``auto`` specifier for pointers
and reference to arrays.
+- Implemented `CWG2521 <https://wg21.link/CWG2521>`_ which reserves using ``__`` in user-defined
+ literal suffixes and deprecates literal operator function declarations using an identifier.
+ Taught ``-Wuser-defined-literals`` for the former, on by default, and added
+ ``-Wdeprecated-literal-operator`` for the latter, off by default for now.
+
+ .. code-block:: c++
+
+ // What follows is warned by -Wuser-defined-literals
+ // albeit "ill-formed, no diagnostic required".
+ // Its behavior is undefined, [reserved.names.general]p2.
+ string operator ""__i18n(const char*, std::size_t);
+
+ // Assume this declaration is not in the global namespace.
+ // -Wdeprecated-literal-operator diagnoses the extra space.
+ string operator "" _i18n(const char*, std::size_t);
+ // ^ an extra space
C Language Changes
------------------
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index c0797166585e44..7b4d415bf06494 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -183,6 +183,7 @@ def DeprecatedCopyWithUserProvidedCopy : DiagGroup<"deprecated-copy-with-user-pr
def DeprecatedCopyWithUserProvidedDtor : DiagGroup<"deprecated-copy-with-user-provided-dtor">;
def DeprecatedCopy : DiagGroup<"deprecated-copy", [DeprecatedCopyWithUserProvidedCopy]>;
def DeprecatedCopyWithDtor : DiagGroup<"deprecated-copy-with-dtor", [DeprecatedCopyWithUserProvidedDtor]>;
+def DeprecatedLiteralOperator : DiagGroup<"deprecated-literal-operator">;
// For compatibility with GCC.
def : DiagGroup<"deprecated-copy-dtor", [DeprecatedCopyWithDtor]>;
def DeprecatedDeclarations : DiagGroup<"deprecated-declarations">;
@@ -220,6 +221,7 @@ def Deprecated : DiagGroup<"deprecated", [DeprecatedAnonEnumEnumConversion,
DeprecatedEnumFloatConversion,
DeprecatedBuiltins,
DeprecatedIncrementBool,
+ DeprecatedLiteralOperator,
DeprecatedPragma,
DeprecatedRegister,
DeprecatedThisCapture,
@@ -865,7 +867,7 @@ def SignedEnumBitfield : DiagGroup<"signed-enum-bitfield">;
def ReservedModuleIdentifier : DiagGroup<"reserved-module-identifier">;
def ReservedIdentifier : DiagGroup<"reserved-identifier",
- [ReservedIdAsMacro, ReservedModuleIdentifier]>;
+ [ReservedIdAsMacro, ReservedModuleIdentifier, UserDefinedLiterals]>;
// Unreachable code warning groups.
//
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index d9932e0aa31a2a..52cca5acfd9245 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -406,6 +406,9 @@ def warn_reserved_extern_symbol: Warning<
"it starts with '_' followed by a capital letter|"
"it contains '__'}1">,
InGroup<ReservedIdentifier>, DefaultIgnore;
+def warn_deprecated_literal_operator_id: Warning<
+ "identifier %0 preceded by whitespace in a literal operator declaration "
+ "is deprecated">, InGroup<DeprecatedLiteralOperator>, DefaultIgnore;
def warn_reserved_module_name : Warning<
"%0 is a reserved name for a module">, InGroup<ReservedModuleIdentifier>;
@@ -9261,8 +9264,8 @@ def ext_string_literal_operator_template : ExtWarn<
"string literal operator templates are a GNU extension">,
InGroup<GNUStringLiteralOperatorTemplate>;
def warn_user_literal_reserved : Warning<
- "user-defined literal suffixes not starting with '_' are reserved"
- "%select{; no literal will invoke this operator|}0">,
+ "user-defined literal suffixes %select{<ERROR>|not starting with '_'|containing '__'}0 are reserved"
+ "%select{; no literal will invoke this operator|}1">,
InGroup<UserDefinedLiterals>;
// C++ conversion functions
diff --git a/clang/include/clang/Basic/IdentifierTable.h b/clang/include/clang/Basic/IdentifierTable.h
index 2c7ce0e4b97532..f87f7671481579 100644
--- a/clang/include/clang/Basic/IdentifierTable.h
+++ b/clang/include/clang/Basic/IdentifierTable.h
@@ -50,6 +50,12 @@ enum class ReservedIdentifierStatus {
ContainsDoubleUnderscore,
};
+enum class ReservedLiteralSuffixIdStatus {
+ NotReserved = 0,
+ NotStartsWithUnderscore,
+ ContainsDoubleUnderscore,
+};
+
/// Determine whether an identifier is reserved for use as a name at global
/// scope. Such identifiers might be implementation-specific global functions
/// or variables.
@@ -491,6 +497,10 @@ class alignas(IdentifierInfoAlignment) IdentifierInfo {
/// 7.1.3, C++ [lib.global.names]).
ReservedIdentifierStatus isReserved(const LangOptions &LangOpts) const;
+ /// Determine whether \p this is a name reserved for future standardization or
+ /// the implementation (C++ [usrlit.suffix]).
+ ReservedLiteralSuffixIdStatus isReservedLiteralSuffixId() const;
+
/// If the identifier is an "uglified" reserved name, return a cleaned form.
/// e.g. _Foo => Foo. Otherwise, just returns the name.
StringRef deuglifiedName() const;
diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
index 661e9f79579a6b..0065a6173c2003 100644
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -397,6 +397,19 @@ IdentifierInfo::isReserved(const LangOptions &LangOpts) const {
return ReservedIdentifierStatus::NotReserved;
}
+ReservedLiteralSuffixIdStatus
+IdentifierInfo::isReservedLiteralSuffixId() const {
+ StringRef Name = getName();
+
+ if (Name[0] != '_')
+ return ReservedLiteralSuffixIdStatus::NotStartsWithUnderscore;
+
+ if (Name.contains("__"))
+ return ReservedLiteralSuffixIdStatus::ContainsDoubleUnderscore;
+
+ return ReservedLiteralSuffixIdStatus::NotReserved;
+}
+
StringRef IdentifierInfo::deuglifiedName() const {
StringRef Name = getName();
if (Name.size() >= 2 && Name.front() == '_' &&
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 5c68642712a8a5..4848af9ade35b3 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -16447,15 +16447,18 @@ bool Sema::CheckLiteralOperatorDeclaration(FunctionDecl *FnDecl) {
}
}
- StringRef LiteralName
- = FnDecl->getDeclName().getCXXLiteralIdentifier()->getName();
- if (LiteralName[0] != '_' &&
+ const IdentifierInfo *II = FnDecl->getDeclName().getCXXLiteralIdentifier();
+ ReservedLiteralSuffixIdStatus Status = II->isReservedLiteralSuffixId();
+ if (Status != ReservedLiteralSuffixIdStatus::NotReserved &&
!getSourceManager().isInSystemHeader(FnDecl->getLocation())) {
- // C++11 [usrlit.suffix]p1:
- // Literal suffix identifiers that do not start with an underscore
- // are reserved for future standardization.
+ // C++23 [usrlit.suffix]p1:
+ // Literal suffix identifiers that do not start with an underscore are
+ // reserved for future standardization. Literal suffix identifiers that
+ // contain a double underscore __ are reserved for use by C++
+ // implementations.
Diag(FnDecl->getLocation(), diag::warn_user_literal_reserved)
- << StringLiteralParser::isValidUDSuffix(getLangOpts(), LiteralName);
+ << static_cast<int>(Status)
+ << StringLiteralParser::isValidUDSuffix(getLangOpts(), II->getName());
}
return false;
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 168a0f354683d8..3e43b69dc8bb29 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -502,13 +502,16 @@ bool Sema::checkLiteralOperatorId(const CXXScopeSpec &SS,
IdentifierInfo *II = Name.Identifier;
ReservedIdentifierStatus Status = II->isReserved(PP.getLangOpts());
SourceLocation Loc = Name.getEndLoc();
- if (isReservedInAllContexts(Status) &&
- !PP.getSourceManager().isInSystemHeader(Loc)) {
- Diag(Loc, diag::warn_reserved_extern_symbol)
- << II << static_cast<int>(Status)
- << FixItHint::CreateReplacement(
- Name.getSourceRange(),
- (StringRef("operator\"\"") + II->getName()).str());
+ if (!PP.getSourceManager().isInSystemHeader(Loc)) {
+ if (auto Hint = FixItHint::CreateReplacement(
+ Name.getSourceRange(),
+ (StringRef("operator\"\"") + II->getName()).str());
+ isReservedInAllContexts(Status)) {
+ Diag(Loc, diag::warn_reserved_extern_symbol)
+ << II << static_cast<int>(Status) << Hint;
+ } else {
+ Diag(Loc, diag::warn_deprecated_literal_operator_id) << II << Hint;
+ }
}
}
diff --git a/clang/test/CXX/drs/dr25xx.cpp b/clang/test/CXX/drs/dr25xx.cpp
index b41f026e629f02..a535f65e085608 100644
--- a/clang/test/CXX/drs/dr25xx.cpp
+++ b/clang/test/CXX/drs/dr25xx.cpp
@@ -1,4 +1,14 @@
-// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify
+// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+
+#if __cplusplus < 201103L
+// expected-no-diagnostics
+#endif
namespace dr2516 { // dr2516: yes
// NB: reusing 1482 test
@@ -13,9 +23,13 @@ enum E2 : S<E2>::I { e };
namespace dr2518 { // dr2518: 17
+#if __cplusplus >= 201103L
template <class T>
void f(T t) {
if constexpr (sizeof(T) != sizeof(int)) {
+#if __cplusplus < 201703L
+// expected-error at -2 {{constexpr if is a C++17 extension}}
+#endif
static_assert(false, "must be int-sized"); // expected-error {{must be int-size}}
}
}
@@ -28,6 +42,9 @@ void g(char c) {
template <typename Ty>
struct S {
static_assert(false); // expected-error {{static assertion failed}}
+#if __cplusplus < 201703L
+// expected-error at -2 {{'static_assert' with no message is a C++17 extension}}
+#endif
};
template <>
@@ -41,11 +58,31 @@ int test_specialization() {
S<float> s2;
S<double> s3; // expected-note {{in instantiation of template class 'dr2518::S<double>' requested here}}
}
+#endif
}
+namespace dr2521 { // dr2521: 17
+#if __cplusplus >= 201103L
+#pragma clang diagnostic push
+#pragma clang diagnostic warning "-Wdeprecated-literal-operator"
+long double operator"" _\u03C0___(long double);
+// expected-warning at -1 {{identifier '_π___' preceded by whitespace in a literal operator declaration is deprecated}}
+// expected-warning at -2 {{user-defined literal suffixes containing '__' are reserved}}
+
+template <char... Chars> decltype(sizeof 0)
+operator"" _div();
+// expected-warning at -1 {{identifier '_div' preceded by whitespace in a literal operator declaration is deprecated}}
+
+using ::dr2521::operator"" _\u03C0___;
+using ::dr2521::operator""_div;
+// expected-warning at -2 {{identifier '_π___' preceded by whitespace in a literal operator declaration is deprecated}}
+#pragma clang diagnostic pop
+#endif
+} // namespace dr2521
namespace dr2565 { // dr2565: 16 open
+#if __cplusplus >= 202002L
template<typename T>
concept C = requires (typename T::type x) {
x + 1;
@@ -107,4 +144,5 @@ namespace dr2565 { // dr2565: 16 open
// expected-error at -1{{static assertion failed}}
// expected-note at -2{{because substituted constraint expression is ill-formed: constraint depends on a previously diagnosed expression}}
+#endif
}
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 07c51401b6b41e..c950b5b08d1afa 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -14933,7 +14933,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://cplusplus.github.io/CWG/issues/2521.html">2521</a></td>
<td>DR</td>
<td>User-defined literals and reserved identifiers</td>
- <td class="none" align="center">Unknown</td>
+ <td class="unreleased" align="center">Clang 17</td>
</tr>
<tr class="open" id="2522">
<td><a href="https://cplusplus.github.io/CWG/issues/2522.html">2522</a></td>
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