c++/reflection: Reject invalid annotation on class [PR123609]
The C++ compiler now rejects invalid attributes on class declarations, improving error reporting.
This commit fixes an issue where the C++ compiler ignored certain errors when parsing attributes on class declarations due to tentative parsing. Now the compiler re-parses attributes that previously caused a tentative parsing failure, ensuring that invalid attributes are rejected and appropriate errors are reported. This change improves the robustness of the compiler’s error handling and provides more informative diagnostics to the user.
In Details
The commit modifies cp_parser_class_head in gcc/cp/parser.cc to re-parse attributes that caused a tentative parsing failure. This ensures that invalid attributes on class declarations are properly rejected instead of being ignored. This change is related to C++ reflection features. The commit also adjusts the expected errors in g++.dg/cpp0x/attr-nodiscard1.C and adds a new test case g++.dg/reflect/annotations19.C to verify the fix for PR c++/123609.
For Context
C++ reflection is a feature that allows a program to inspect and modify its own structure and behavior at runtime. Attributes (using the [[...]] syntax) are annotations that can be added to various parts of the code, including class declarations. This commit ensures that the compiler correctly identifies and rejects invalid attributes applied to classes, which helps in preventing unexpected behavior and improving code quality by reporting errors early in the development process.