Attribute Diagnostics¶

Attributes use the same comptime diagnostics API as other comptime code.

Diagnostics owns Compiler.note, Compiler.warn, Compiler.err, and structured diagnostic payloads.

Compiler.note(.{ .message = "message" })
Compiler.warn(.{ .message = "message" })
Compiler.err(.{ .message = "message" })

Locations¶

• Attribute provider errors should use the attribute use site as the primary location.
• Notes may point into the provider implementation when helpful.
• Errors from registering an attribute provider with @attribute point at the provider declaration.

Hard Errors and Lints¶

Sema rejects invalid attribute structure before provider execution when:

• the attribute name cannot be resolved;
• the resolved declaration is not a registered attribute provider;
• the provider target list does not include the actual target kind;
• a non-repeatable provider is applied more than once to the same target;
• attribute argument arity, type, or comptime checks fail;
• the target site is not a V1 attribute target.

Provider execution rejects the program when the provider calls Compiler.err, returns an unhandled error, or trips a target setter validation error.

Lints own redundant but valid combinations, suspicious order dependence, and policy diagnostics that must be stable independent of comptime caching. Provider warnings and notes are execution-time comptime effects and are not required to replay when a successful cached provider result is reused.

Deferred¶

For provider-specific source locations, pass an explicit structured payload:

Compiler.err(.{
  .message = "@resource requires Disposable",
  .primary = context.source(),
  .notes = .{
    .{
      .message = "add struct(Disposable)",
      .source = context.source(),
    },
  },
})