gccrs: Add missing context ast walker to check for free fn's
gccrs now includes a necessary AST visitor for checking free functions.
This commit introduces a missing ContextualASTVisitor to gccrs, which is essential for correctly checking free functions. The addition ensures that the compiler can properly traverse and analyze the Abstract Syntax Tree (AST) to identify and validate standalone functions. This resolves an issue related to Rust-GCC/gccrs#3585, improving the compiler’s ability to handle free function declarations.
In Details
The gccrs frontend's AST manipulation infrastructure is enhanced with the addition of a ContextualASTVisitor in ast/rust-ast-visitor.cc and its prototype in ast/rust-ast-visitor.h. This visitor is crucial for context-aware analysis, particularly for correctly processing free functions (functions not associated with any type or trait). Its absence was preventing proper checks, as noted in Rust-GCC/gccrs#3585. The visitor's visit method is now implemented to facilitate these checks.
- context ast walker
- A component that traverses the Abstract Syntax Tree (AST) of a program, considering the surrounding context of nodes, to perform specific analyses. In this case, it's for checking free functions in Rust.
- free function
- In Rust, a function that is not defined as a method on a specific type or within an
implblock. It exists independently. - AST
- Abstract Syntax Tree, a tree representation of the abstract syntactic structure of source code.
- visitor pattern
- A behavioral design pattern that allows adding new operations to existing object structures without modifying them. In compilers, it's commonly used for AST traversal.