}];
}
-
-def RequireConstantInitDocs : Documentation {
- let Category = DocCatVariable;
- let Content = [{
-This attribute specifies that the variable to which it is attached is intended
-to have a `constant initializer <http://en.cppreference.com/w/cpp/language/constant_initialization>`_
-according to the rules of [basic.start.static]. The variable is required to
-have static or thread storage duration. If the initialization of the variable
-is not a constant initializer, an error will be produced. This attribute may
-only be used in C++.
-
-Note that in C++03 strict constant expression checking is not done. Instead
-the attribute reports if Clang can emit the the variable as a constant, even
-if it's not technically a 'constant initializer'. This behavior is non-portable.
-
-Static storage duration variables with constant initializers avoid hard-to-find
-bugs caused by the indeterminate order of dynamic initialization. They can also
-be safely used during dynamic initialization across translation units.
-
-This attribute acts as a compile time assertion that the requirements
-for constant initialization have been met. Since these requirements change
-between dialects and have subtle pitfalls it's important to fail fast instead
-of silently falling back on dynamic initialization.
-
-.. code-block:: c++
- // -std=c++14
- #define SAFE_STATIC __attribute__((require_constant_initialization)) static
- struct T {
- constexpr T(int) {}
- ~T(); // non-trivial
- };
- SAFE_STATIC T x = {42}; // Initialization OK. Doesn't check destructor.
- SAFE_STATIC T y = 42; // error: variable does not have a constant initializer
- // copy initialization is not a constant expression on a non-literal type.
- }];
-}
-
def WarnMaybeUnusedDocs : Documentation {
let Category = DocCatVariable;
let Heading = "maybe_unused, unused, gnu::unused";
enumerator, a non-static data member, or a label.
.. code-block: c++
- #include <cassert>
-
- [[maybe_unused]] void f([[maybe_unused]] bool thing1,
- [[maybe_unused]] bool thing2) {
- [[maybe_unused]] bool b = thing1 && thing2;
- assert(b);
+ #include <cassert>\r
+\r
+ [[maybe_unused]] void f([[maybe_unused]] bool thing1,\r
+ [[maybe_unused]] bool thing2) {\r
+ [[maybe_unused]] bool b = thing1 && thing2;\r
+ assert(b);\r
}
}];
}
`void`.
.. code-block: c++
- struct [[nodiscard]] error_info { /*...*/ };
- error_info enable_missile_safety_mode();
-
- void launch_missiles();
- void test_missiles() {
- enable_missile_safety_mode(); // diagnoses
- launch_missiles();
- }
- error_info &foo();
+ struct [[nodiscard]] error_info { /*...*/ };\r
+ error_info enable_missile_safety_mode();\r
+ \r
+ void launch_missiles();\r
+ void test_missiles() {\r
+ enable_missile_safety_mode(); // diagnoses\r
+ launch_missiles();\r
+ }\r
+ error_info &foo();\r
void f() { foo(); } // Does not diagnose, error_info is a reference.
}];
}
Diag(var->getLocation(), diag::warn_missing_variable_declarations) << var;
}
- // Cache the result of checking for constant initialization.
- Optional<bool> CacheHasConstInit;
- const Expr *CacheCulprit;
- auto checkConstInit = [&]() mutable {
- if (!CacheHasConstInit)
- CacheHasConstInit = var->getInit()->isConstantInitializer(
- Context, var->getType()->isReferenceType(), &CacheCulprit);
- return *CacheHasConstInit;
- };
-
if (var->getTLSKind() == VarDecl::TLS_Static) {
+ const Expr *Culprit;
if (var->getType().isDestructedType()) {
// GNU C++98 edits for __thread, [basic.start.term]p3:
// The type of an object with thread storage duration shall not
Diag(var->getLocation(), diag::err_thread_nontrivial_dtor);
if (getLangOpts().CPlusPlus11)
Diag(var->getLocation(), diag::note_use_thread_local);
- } else if (getLangOpts().CPlusPlus && var->hasInit()) {
- if (!checkConstInit()) {
- // GNU C++98 edits for __thread, [basic.start.init]p4:
- // An object of thread storage duration shall not require dynamic
- // initialization.
- // FIXME: Need strict checking here.
- Diag(CacheCulprit->getExprLoc(), diag::err_thread_dynamic_init)
- << CacheCulprit->getSourceRange();
- if (getLangOpts().CPlusPlus11)
- Diag(var->getLocation(), diag::note_use_thread_local);
- }
+ } else if (getLangOpts().CPlusPlus && var->hasInit() &&
+ !var->getInit()->isConstantInitializer(
+ Context, var->getType()->isReferenceType(), &Culprit)) {
+ // GNU C++98 edits for __thread, [basic.start.init]p4:
+ // An object of thread storage duration shall not require dynamic
+ // initialization.
+ // FIXME: Need strict checking here.
+ Diag(Culprit->getExprLoc(), diag::err_thread_dynamic_init)
+ << Culprit->getSourceRange();
+ if (getLangOpts().CPlusPlus11)
+ Diag(var->getLocation(), diag::note_use_thread_local);
}
}
if (!var->getDeclContext()->isDependentContext() &&
Init && !Init->isValueDependent()) {
+ if (IsGlobal && !var->isConstexpr() &&
+ !getDiagnostics().isIgnored(diag::warn_global_constructor,
+ var->getLocation())) {
+ // Warn about globals which don't have a constant initializer. Don't
+ // warn about globals with a non-trivial destructor because we already
+ // warned about them.
+ CXXRecordDecl *RD = baseType->getAsCXXRecordDecl();
+ if (!(RD && !RD->hasTrivialDestructor()) &&
+ !Init->isConstantInitializer(Context, baseType->isReferenceType()))
+ Diag(var->getLocation(), diag::warn_global_constructor)
+ << Init->getSourceRange();
+ }
if (var->isConstexpr()) {
SmallVector<PartialDiagnosticAt, 8> Notes;
// initialized by a constant expression if we check later.
var->checkInitIsICE();
}
-
- // Don't emit further diagnostics about constexpr globals since they
- // were just diagnosed.
- if (!var->isConstexpr() && GlobalStorage &&
- var->hasAttr<RequireConstantInitAttr>()) {
- // FIXME: Need strict checking in C++03 here.
- bool DiagErr = getLangOpts().CPlusPlus11
- ? !var->checkInitIsICE() : !checkConstInit();
- if (DiagErr) {
- auto attr = var->getAttr<RequireConstantInitAttr>();
- Diag(var->getLocation(), diag::err_require_constant_init_failed)
- << Init->getSourceRange();
- Diag(attr->getLocation(), diag::note_declared_required_constant_init_here)
- << attr->getRange();
- }
- }
- else if (!var->isConstexpr() && IsGlobal &&
- !getDiagnostics().isIgnored(diag::warn_global_constructor,
- var->getLocation())) {
- // Warn about globals which don't have a constant initializer. Don't
- // warn about globals with a non-trivial destructor because we already
- // warned about them.
- CXXRecordDecl *RD = baseType->getAsCXXRecordDecl();
- if (!(RD && !RD->hasTrivialDestructor())) {
- if (!checkConstInit())
- Diag(var->getLocation(), diag::warn_global_constructor)
- << Init->getSourceRange();
- }
- }
}
// Require the destructor.
+++ /dev/null
-// RUN: %clang_cc1 -fsyntax-only -verify -DTEST_ONE -std=c++03 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -DTEST_ONE -std=c++11 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -DTEST_ONE -std=c++14 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -DTEST_TWO \
-// RUN: -Wglobal-constructors -std=c++14 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -DTEST_THREE -xc %s
-
-#define ATTR __attribute__((require_constant_initialization)) // expected-note 0+ {{expanded from macro}}
-
-int ReturnInt();
-
-struct PODType {
- int value;
- int value2;
-};
-
-#if defined(__cplusplus)
-
-#if __cplusplus >= 201103L
-struct LitType {
- constexpr LitType() : value(0) {}
- constexpr LitType(int x) : value(x) {}
- LitType(void *) : value(-1) {}
- int value;
-};
-#endif
-
-struct NonLit {
-#if __cplusplus >= 201402L
- constexpr NonLit() : value(0) {}
- constexpr NonLit(int x) : value(x) {}
-#else
- NonLit() : value(0) {}
- NonLit(int x) : value(x) {}
-#endif
- NonLit(void *) : value(-1) {}
- ~NonLit() {}
- int value;
-};
-
-struct StoresNonLit {
-#if __cplusplus >= 201402L
- constexpr StoresNonLit() : obj() {}
- constexpr StoresNonLit(int x) : obj(x) {}
-#else
- StoresNonLit() : obj() {}
- StoresNonLit(int x) : obj(x) {}
-#endif
- StoresNonLit(void *p) : obj(p) {}
- NonLit obj;
-};
-
-#endif // __cplusplus
-
-
-#if defined(TEST_ONE) // Test semantics of attribute
-
-// Test diagnostics when attribute is applied to non-static declarations.
-void test_func_local(ATTR int param) { // expected-error {{only applies to variables with static or thread}}
- ATTR int x = 42; // expected-error {{only applies to variables with static or thread}}
- ATTR extern int y;
-}
-struct ATTR class_mem { // expected-error {{only applies to variables with static or thread}}
- ATTR int x; // expected-error {{only applies to variables with static or thread}}
-};
-
-// [basic.start.static]p2.1
-// if each full-expression (including implicit conversions) that appears in
-// the initializer of a reference with static or thread storage duration is
-// a constant expression (5.20) and the reference is bound to a glvalue
-// designating an object with static storage duration, to a temporary object
-// (see 12.2) or subobject thereof, or to a function;
-
-// Test binding to a static glvalue
-const int glvalue_int = 42;
-const int glvalue_int2 = ReturnInt();
-ATTR const int &glvalue_ref ATTR = glvalue_int;
-ATTR const int &glvalue_ref2 ATTR = glvalue_int2;
-ATTR __thread const int &glvalue_ref_tl = glvalue_int;
-
-void test_basic_start_static_2_1() {
- const int non_global = 42;
- ATTR static const int &local_init = non_global; // expected-error {{variable does not have a constant initializer}}
- // expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
- ATTR static const int &global_init = glvalue_int;
- ATTR static const int &temp_init = 42;
-}
-
-ATTR const int &temp_ref = 42;
-ATTR const int &temp_ref2 = ReturnInt(); // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR const NonLit &nl_temp_ref = 42; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-
-#if __cplusplus >= 201103L
-ATTR const LitType &lit_temp_ref = 42;
-ATTR const int &subobj_ref = LitType{}.value;
-#endif
-
-ATTR const int &nl_subobj_ref = NonLit().value; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-
-struct TT1 {
- ATTR static const int &no_init;
- ATTR static const int &glvalue_init;
- ATTR static const int &temp_init;
- ATTR static const int &subobj_init;
-#if __cplusplus >= 201103L
- ATTR static thread_local const int &tl_glvalue_init;
- ATTR static thread_local const int &tl_temp_init; // expected-note {{required by 'require_constant_initializer' attribute here}}
-#endif
-};
-const int &TT1::glvalue_init = glvalue_int;
-const int &TT1::temp_init = 42;
-const int &TT1::subobj_init = PODType().value;
-#if __cplusplus >= 201103L
-thread_local const int &TT1::tl_glvalue_init = glvalue_int;
-thread_local const int &TT1::tl_temp_init = 42; // expected-error {{variable does not have a constant initializer}}
-#endif
-
-// [basic.start.static]p2.2
-// if an object with static or thread storage duration is initialized by a
-// constructor call, and if the initialization full-expression is a constant
-// initializer for the object;
-
-void test_basic_start_static_2_2() {
-#if __cplusplus < 201103L
- ATTR static PODType pod;
-#else
- ATTR static PODType pod; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-#endif
- ATTR static PODType pot2 = {ReturnInt()}; // expected-error {{variable does not have a constant initializer}}
- // expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-
-#if __cplusplus >= 201103L
- constexpr LitType l;
- ATTR static LitType static_lit = l;
- ATTR static LitType static_lit2 = (void *)0; // expected-error {{variable does not have a constant initializer}}
- // expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
- ATTR static LitType static_lit3 = ReturnInt(); // expected-error {{variable does not have a constant initializer}}
- // expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
- ATTR thread_local LitType tls = 42;
-#endif
-}
-
-struct TT2 {
- ATTR static PODType pod_noinit;
-#if __cplusplus >= 201103L
-// expected-note@-2 {{required by 'require_constant_initializer' attribute here}}
-#endif
- ATTR static PODType pod_copy_init; // expected-note {{required by 'require_constant_initializer' attribute here}}
-#if __cplusplus >= 201402L
- ATTR static constexpr LitType lit = {};
- ATTR static const NonLit non_lit;
- ATTR static const NonLit non_lit_list_init;
- ATTR static const NonLit non_lit_copy_init; // expected-note {{required by 'require_constant_initializer' attribute here}}
-#endif
-};
-PODType TT2::pod_noinit;
-#if __cplusplus >= 201103L
-// expected-error@-2 {{variable does not have a constant initializer}}
-#endif
-PODType TT2::pod_copy_init(TT2::pod_noinit); // expected-error {{variable does not have a constant initializer}}
-#if __cplusplus >= 201402L
-const NonLit TT2::non_lit(42);
-const NonLit TT2::non_lit_list_init = {42};
-const NonLit TT2::non_lit_copy_init = 42; // expected-error {{variable does not have a constant initializer}}
-#endif
-
-#if __cplusplus >= 201103L
-ATTR LitType lit_ctor;
-ATTR LitType lit_ctor2{};
-ATTR LitType lit_ctor3 = {};
-ATTR __thread LitType lit_ctor_tl = {};
-
-#if __cplusplus >= 201402L
-ATTR NonLit nl_ctor;
-ATTR NonLit nl_ctor2{};
-ATTR NonLit nl_ctor3 = {};
-ATTR thread_local NonLit nl_ctor_tl = {};
-ATTR StoresNonLit snl;
-#else
-ATTR NonLit nl_ctor; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR NonLit nl_ctor2{}; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR NonLit nl_ctor3 = {}; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR thread_local NonLit nl_ctor_tl = {}; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR StoresNonLit snl; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-#endif
-
-// Non-literal types cannot appear in the initializer of a non-literal type.
-ATTR int nl_in_init = NonLit{42}.value; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR int lit_in_init = LitType{42}.value;
-#endif
-
-// [basic.start.static]p2.3
-// if an object with static or thread storage duration is not initialized by a
-// constructor call and if either the object is value-initialized or every
-// full-expression that appears in its initializer is a constant expression.
-void test_basic_start_static_2_3() {
- ATTR static int static_local = 42;
- ATTR static int static_local2; // zero-initialization takes place
-#if __cplusplus >= 201103L
- ATTR thread_local int tl_local = 42;
-#endif
-}
-
-ATTR int no_init; // zero initialization takes place
-ATTR int arg_init = 42;
-ATTR PODType pod_init = {};
-ATTR PODType pod_missing_init = {42 /* should have second arg */};
-ATTR PODType pod_full_init = {1, 2};
-ATTR PODType pod_non_constexpr_init = {1, ReturnInt()}; // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-
-#if __cplusplus >= 201103L
-ATTR int val_init{};
-ATTR int brace_init = {};
-#endif
-
-ATTR __thread int tl_init = 0;
-typedef const char *StrType;
-
-#if __cplusplus >= 201103L
-
-// Test that the validity of the selected constructor is checked, not just the
-// initializer
-struct NotC {
- constexpr NotC(void *) {}
- NotC(int) {}
-};
-template <class T>
-struct TestCtor {
- constexpr TestCtor(int x) : value(x) {}
- T value;
-};
-ATTR TestCtor<NotC> t(42); // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-#endif
-
-// Test various array types
-ATTR const char *foo[] = {"abc", "def"};
-ATTR PODType bar[] = {{}, {123, 456}};
-
-#elif defined(TEST_TWO) // Test for duplicate warnings
-struct NotC {
- constexpr NotC(void *) {}
- NotC(int) {} // expected-note 2 {{declared here}}
-};
-template <class T>
-struct TestCtor {
- constexpr TestCtor(int x) : value(x) {} // expected-note 2 {{non-constexpr constructor}}
- T value;
-};
-
-ATTR LitType non_const_lit(nullptr); // expected-error {{variable does not have a constant initializer}}
-// expected-note@-1 {{required by 'require_constant_initializer' attribute here}}
-ATTR NonLit non_const(nullptr); // expected-error {{variable does not have a constant initializer}}
-// expected-warning@-1 {{declaration requires a global destructor}}
-// expected-note@-2 {{required by 'require_constant_initializer' attribute here}}
-LitType const_init_lit(nullptr); // expected-warning {{declaration requires a global constructor}}
-NonLit const_init{42}; // expected-warning {{declaration requires a global destructor}}
-constexpr TestCtor<NotC> inval_constexpr(42); // expected-error {{must be initialized by a constant expression}}
-// expected-note@-1 {{in call to 'TestCtor(42)'}}
-ATTR constexpr TestCtor<NotC> inval_constexpr2(42); // expected-error {{must be initialized by a constant expression}}
-// expected-note@-1 {{in call to 'TestCtor(42)'}}
-
-#elif defined(TEST_THREE)
-#if defined(__cplusplus)
-#error This test requires C
-#endif
-// Test that using the attribute in C results in a diagnostic
-ATTR int x = 0; // expected-warning {{attribute ignored}}
-#else
-#error No test case specified
-#endif // defined(TEST_N)
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