forked from OSchip/llvm-project
Revert r124217 because it didn't catch the actual error case it was trying to
catch: lock_guard(my_mutex); declares a variable instead of creating a temporary. llvm-svn: 124398
This commit is contained in:
Jeffrey Yasskin
parent
1cec755494
commit
bbc4eea2c2
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@ -25,7 +25,6 @@ td {
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<li><a href="#vectors">Vectors and Extended Vectors</a></li>
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<li><a href="#deprecated">Messages on <tt>deprecated</tt> and <tt>unavailable</tt> attributes</a></li>
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<li><a href="#attributes-on-enumerators">Attributes on enumerators</a></li>
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<li><a href="#forbid-temporaries-attribute">Attribute to forbid temporaries of a type</a></li>
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<li><a href="#checking_language_features">Checks for Standard Language Features</a></li>
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<ul>
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<li><a href="#cxx_exceptions">C++ exceptions</a></li>
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@ -342,33 +341,6 @@ individual enumerators.</p>
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<p>Query for this feature with <tt>__has_feature(enumerator_attributes)</tt>.</p>
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<!-- ======================================================================= -->
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<h2 id="forbid-temporaries-attribute">Attribute to forbid temporaries of a type</h2>
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<!-- ======================================================================= -->
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<p>Clang provides a <tt>forbid_temporaries</tt> attribute to forbid
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temporaries of a particular type.</p>
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<blockquote>
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<pre>class __attribute__((forbid_temporaries)) scoped_lock {
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...
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};</pre>
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</blockquote>
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<p>This prevents mistakes like</p>
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<blockquote>
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<pre>void foo() {
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scoped_lock(my_mutex);
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// Forgot the local variable name, so destructor runs here.
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code_that_needs_lock_held();
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// User expects destructor to run here.
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};</pre>
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</blockquote>
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<p>Query for this feature with <tt>__has_attribute(forbid_temporaries)</tt>.
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Use <tt>-Wno-forbid-temporaries</tt> to disable the resulting warning.</p>
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<!-- ======================================================================= -->
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<h2 id="checking_language_features">Checks for Standard Language Features</h2>
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<!-- ======================================================================= -->
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@ -232,11 +232,6 @@ def Final : InheritableAttr {
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let Spellings = [];
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}
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def ForbidTemporaries : Attr {
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let Spellings = ["forbid_temporaries"];
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let Subjects = [CXXRecord];
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}
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def Format : InheritableAttr {
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let Spellings = ["format"];
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let Args = [StringArgument<"Type">, IntArgument<"FormatIdx">,
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@ -861,9 +861,6 @@ def err_temp_copy_deleted : Error<
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"of type %1 invokes deleted constructor">;
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def err_temp_copy_incomplete : Error<
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"copying a temporary object of incomplete type %0">;
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def warn_temporaries_forbidden : Warning<
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"must not create temporaries of type %0">,
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InGroup<DiagGroup<"forbid-temporaries">>;
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// C++0x decltype
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def err_cannot_determine_declared_type_of_overloaded_function : Error<
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@ -104,7 +104,6 @@ public:
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AT_dllimport,
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AT_ext_vector_type,
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AT_fastcall,
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AT_forbid_temporaries,
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AT_format,
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AT_format_arg,
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AT_global,
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@ -85,7 +85,6 @@ AttributeList::Kind AttributeList::getKind(const IdentifierInfo *Name) {
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.Case("deprecated", AT_deprecated)
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.Case("visibility", AT_visibility)
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.Case("destructor", AT_destructor)
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.Case("forbid_temporaries", AT_forbid_temporaries)
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.Case("format_arg", AT_format_arg)
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.Case("gnu_inline", AT_gnu_inline)
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.Case("weak_import", AT_weak_import)
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@ -885,24 +885,6 @@ static void HandleVecReturnAttr(Decl *d, const AttributeList &Attr,
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d->addAttr(::new (S.Context) VecReturnAttr(Attr.getLoc(), S.Context));
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}
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static void HandleForbidTemporariesAttr(Decl *d, const AttributeList &Attr,
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Sema &S) {
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assert(Attr.isInvalid() == false);
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if (Attr.getNumArgs() != 0) {
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S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
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return;
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}
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if (!isa<TypeDecl>(d)) {
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S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
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<< Attr.getName() << 9 /*class*/;
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return;
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}
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d->addAttr(::new (S.Context) ForbidTemporariesAttr(Attr.getLoc(), S.Context));
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}
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static void HandleDependencyAttr(Decl *d, const AttributeList &Attr, Sema &S) {
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if (!isFunctionOrMethod(d) && !isa<ParmVarDecl>(d)) {
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S.Diag(Attr.getLoc(), diag::err_attribute_wrong_decl_type)
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@ -2692,8 +2674,6 @@ static void ProcessInheritableDeclAttr(Scope *scope, Decl *D,
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case AttributeList::AT_ext_vector_type:
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HandleExtVectorTypeAttr(scope, D, Attr, S);
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break;
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case AttributeList::AT_forbid_temporaries:
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HandleForbidTemporariesAttr(D, Attr, S); break;
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case AttributeList::AT_format: HandleFormatAttr (D, Attr, S); break;
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case AttributeList::AT_format_arg: HandleFormatArgAttr (D, Attr, S); break;
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case AttributeList::AT_global: HandleGlobalAttr (D, Attr, S); break;
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@ -3294,12 +3294,9 @@ ExprResult Sema::MaybeBindToTemporary(Expr *E) {
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}
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}
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CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
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if (RD->getAttr<ForbidTemporariesAttr>())
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Diag(E->getExprLoc(), diag::warn_temporaries_forbidden) << E->getType();
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// That should be enough to guarantee that this type is complete.
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// If it has a trivial destructor, we can avoid the extra copy.
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CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
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if (RD->isInvalidDecl() || RD->hasTrivialDestructor())
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return Owned(E);
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@ -1,50 +0,0 @@
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// RUN: %clang_cc1 -fsyntax-only -verify %s
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#if !__has_attribute(forbid_temporaries)
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#error "Should support forbid_temporaries attribute"
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#endif
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class __attribute__((forbid_temporaries)) NotATemporary {
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};
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class __attribute__((forbid_temporaries(1))) ShouldntHaveArguments { // expected-error {{attribute requires 0 argument(s)}}
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};
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void bad_function() __attribute__((forbid_temporaries)); // expected-warning {{'forbid_temporaries' attribute only applies to classes}}
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int var __attribute__((forbid_temporaries)); // expected-warning {{'forbid_temporaries' attribute only applies to classes}}
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void bar(const NotATemporary&);
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void foo() {
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NotATemporary this_is_fine;
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bar(NotATemporary()); // expected-warning {{must not create temporaries of type 'NotATemporary'}}
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NotATemporary(); // expected-warning {{must not create temporaries of type 'NotATemporary'}}
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}
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// Check that the above restrictions work for templates too.
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template<typename T>
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class __attribute__((forbid_temporaries)) NotATemporaryTpl {
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};
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template<typename T>
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void bar_tpl(const NotATemporaryTpl<T>&);
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void tpl_user() {
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NotATemporaryTpl<int> this_is_fine;
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bar_tpl(NotATemporaryTpl<int>()); // expected-warning {{must not create temporaries of type 'NotATemporaryTpl<int>'}}
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NotATemporaryTpl<int>(); // expected-warning {{must not create temporaries of type 'NotATemporaryTpl<int>'}}
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}
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// Test that a specialization can override the template's default.
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struct TemporariesOk;
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template<> class NotATemporaryTpl<TemporariesOk> {
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};
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void specialization_user() {
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NotATemporaryTpl<TemporariesOk> this_is_fine;
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bar_tpl(NotATemporaryTpl<TemporariesOk>());
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NotATemporaryTpl<TemporariesOk>();
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}
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