gccrs: Emit function-scope drops for unit tail expressions
GCC's Rust compiler now emits necessary drop calls for unit tail expressions.
GCC’s Rust compiler now correctly emits drop calls for unit tail expressions within functions. This ensures that any resources held by variables in scope are properly cleaned up before the function returns, particularly when the function’s last expression implicitly returns a unit type. This fix addresses a gap in resource management for such cases.
In Details
The HIRCompileBase::compile_function_body in rustc_codegen_gcc has been updated to emit current scope drops specifically for 'unit tail expressions.' These are expressions that form the value of a block and evaluate to the unit type (). Previously, explicit drop calls might have been missed for variables in scope just before returning from such expressions. This commit ensures that Drop glue is correctly generated, maintaining RAII guarantees.
- unit tail expression
- In Rust, an expression that forms the value of a block and results in the unit type
(). If it's the last expression in a block and has no semicolon, it's the block's value. If it returns(), it's a unit tail expression. - Drop
- In Rust, a trait that can be implemented for a type to define custom logic that runs when a value of that type goes out of scope. This is primarily used for resource management.
- RAII
- Resource Acquisition Is Initialization. A programming idiom in which resource management is tied to object lifetime. In Rust, this is primarily handled via the
Droptrait.