This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 113d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-04-05
According to 9.12.1 [dcl.attr.grammar] paragraph 5,
Each attribute-specifier-seq is said to appertain to some entity or statement, identified by the syntactic context where it appears ( Clause 8 [stmt.stmt], 9.1 [dcl.pre], 9.3 [dcl.decl]). If an attribute-specifier-seq that appertains to some entity or statement contains an attribute or alignment-specifier that is not allowed to apply to that entity or statement, the program is ill-formed.
This does not, but presumably should, mention contract-attribute-specifiers.
Proposed resolution (March, 2019):
Change 9.12.1 [dcl.attr.grammar] paragraph 5 as follows:
Each attribute-specifier-seq is said to appertain to some entity or statement, identified by the syntactic context where it appears (Clause 8 [stmt.stmt], 9.1 [dcl.pre], 9.3 [dcl.decl]). If an attribute-specifier-seq that appertains to some entity or statement contains an attribute, contract-attribute-specifier, or alignment-specifier that is not allowed to apply to that entity or statement, the program is ill-formed. If an attribute-specifier-seq appertains to a friend declaration (11.8.4 [class.friend]), that declaration shall be a definition. No attribute-specifier-seq shall appertain to an explicit instantiation (13.9.3 [temp.explicit]).
Rationale (July, 2019):
With the adoption of paper P1823R0, removing contracts from C++20, this issue is moot.