diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 125d51c42d507..3b4a9291b6f7f 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -163,6 +163,9 @@ C23 Feature Support - Clang now supports `N3018 The constexpr specifier for object definitions` `_. +- Clang now diagnoses `N3006 Underspecified object declarations + `_. + Non-comprehensive list of changes in this release ------------------------------------------------- diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 8e97902564af0..b336b5f63367c 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -7685,6 +7685,8 @@ def err_attribute_arm_mve_polymorphism : Error< "'__clang_arm_mve_strict_polymorphism' attribute can only be applied to an MVE/NEON vector type">; def err_attribute_webassembly_funcref : Error< "'__funcref' attribute can only be applied to a function pointer type">; +def err_c23_underspecified_object_declaration: Error< + "'%select{struct||union||enum}0 %1' is defined as an underspecified object initializer">; def warn_setter_getter_impl_required : Warning< "property %0 requires method %1 to be defined - " diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 8725b09f8546c..bb6004d6fc3cb 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -7813,6 +7813,32 @@ Sema::BuildCompoundLiteralExpr(SourceLocation LParenLoc, TypeSourceInfo *TInfo, diag::err_variable_object_no_init)) return ExprError(); } + } else if (LangOpts.C23 && + (literalType->isRecordType() || literalType->isEnumeralType())) { + // C23 6.2.1p7: Structure, union, and enumeration tags have scope that + // begins just after the appearance of the tag in a type specifier that + // declares the tag. + // [...] + // An ordinary identifier that has an underspecified definition has scope + // that starts when the definition is completed; if the same ordinary + // identifier declares another entity with a scope that encloses the current + // block, that declaration is hidden as soon as the inner declarator is + // completed*.) + // [...] + // *) That means, that the outer declaration is not visible for the + // initializer. + auto Range = SourceRange(LParenLoc, RParenLoc); + const auto *Tag = literalType->castAs(); + const auto &TagRange = Tag->getDecl()->getSourceRange(); + + // We should diagnose underspecified declaration, unless the identifier has + // been diagnosed as being a redefinition, since the tag is made anonymous. + if (Range.fullyContains(TagRange) && Tag->getDecl()->getIdentifier()) { + Diag(TagRange.getBegin(), diag::err_c23_underspecified_object_declaration) + << (unsigned)Tag->getDecl()->getTagKind() << Tag->getDecl()->getName() + << TagRange; + return ExprError(); + } } else if (!literalType->isDependentType() && RequireCompleteType(LParenLoc, literalType, diag::err_typecheck_decl_incomplete_type, diff --git a/clang/test/C/C2x/n3006.c b/clang/test/C/C2x/n3006.c new file mode 100644 index 0000000000000..15efc0ccd6d32 --- /dev/null +++ b/clang/test/C/C2x/n3006.c @@ -0,0 +1,27 @@ +// RUN: %clang_cc1 -std=c2x -verify %s + +/* WG14 N3006: Full + * Underspecified object declarations + */ + +struct S1 { int x, y; }; // expected-note {{previous definition is here}} +union U1 { int a; double b; }; // expected-note {{previous definition is here}} +enum E1 { FOO, BAR }; // expected-note {{previous definition is here}} + +auto normal_struct = (struct S1){ 1, 2 }; +auto underspecified_struct = (struct S2 { int x, y; }){ 1, 2 }; // expected-error {{'struct S2' is defined as an underspecified object initializer}} +auto underspecified_struct_redef = (struct S1 { char x, y; }){ 'A', 'B'}; // expected-error {{redefinition of 'S1'}} +auto underspecified_empty_struct = (struct S3 { }){ }; // expected-error {{'struct S3' is defined as an underspecified object initializer}} + +auto normal_union_int = (union U1){ .a = 12 }; +auto normal_union_double = (union U1){ .b = 2.4 }; +auto underspecified_union = (union U2 { int a; double b; }){ .a = 34 }; // expected-error {{'union U2' is defined as an underspecified object initializer}} +auto underspecified_union_redef = (union U1 { char a; double b; }){ .a = 'A' }; // expected-error {{redefinition of 'U1'}} +auto underspecified_empty_union = (union U3 { }){ }; // expected-error {{'union U3' is defined as an underspecified object initializer}} + +auto normal_enum_foo = (enum E1){ FOO }; +auto normal_enum_bar = (enum E1){ BAR }; +auto underspecified_enum = (enum E2 { BAZ, QUX }){ BAZ }; // expected-error {{'enum E2' is defined as an underspecified object initializer}} +auto underspecified_enum_redef = (enum E1 { ONE, TWO }){ ONE }; // expected-error {{redefinition of 'E1'}} +auto underspecified_empty_enum = (enum E3 { }){ }; // expected-error {{'enum E3' is defined as an underspecified object initializer}} \ + expected-error {{use of empty enum}} diff --git a/clang/test/Parser/c2x-underspecified-decls.c b/clang/test/Parser/c2x-underspecified-decls.c new file mode 100644 index 0000000000000..5a7e935cda544 --- /dev/null +++ b/clang/test/Parser/c2x-underspecified-decls.c @@ -0,0 +1,12 @@ +// RUN: %clang_cc1 -fsyntax-only -verify=expected,c23 -std=c23 %s +// RUN: %clang_cc1 -fsyntax-only -verify=expected,c17 -std=c17 %s + +auto underspecified_struct = (struct S1 { int x, y; }){ 1, 2 }; // c23-error {{'struct S1' is defined as an underspecified object initializer}} \ + c17-error {{type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int}} \ + c17-error {{illegal storage class on file-scoped variable}} +auto underspecified_union = (union U1 { int a; double b; }){ .a = 34 }; // c23-error {{'union U1' is defined as an underspecified object initializer}} \ + c17-error {{type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int}} \ + c17-error {{illegal storage class on file-scoped variable}} +auto underspecified_enum = (enum E1 { FOO, BAR }){ BAR }; // c23-error {{'enum E1' is defined as an underspecified object initializer}} \ + c17-error {{type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int}} \ + c17-error {{illegal storage class on file-scoped variable}} diff --git a/clang/www/c_status.html b/clang/www/c_status.html index 9e4600b3e66ac..6abd119914723 100644 --- a/clang/www/c_status.html +++ b/clang/www/c_status.html @@ -1191,7 +1191,7 @@

C23 implementation status

Underspecified object definitions N3006 - No + Clang 19 Type inference for object declarations