rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names #148279
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… user-defined function names
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| // A simple ident for a lambda, using the user's function name within it to avoid collisions. | ||
| let param_name = format!("__bench_{}", fn_.ident.name); | ||
| let bencher_param = Ident::new(Symbol::intern(¶m_name), attr_sp); |
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why did you change it from from_str_and_span to new + intern?
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It’s mostly a style preference, @oli-obk. Since format! gives us a String (unlike the old str), we still need either a conversion or an interning step - from_str_and_span would need a .as_str() call, while new needs a Symbol::intern call. So from_str_and_span doesn’t really simplify anything, and I think the explicit intern call makes it flow a bit clearer and cleaner than a conversion, and also separates the logical steps of building the string and then interning it. That said, if you’d rather keep from_str_and_span and just add .as_str() for consistency, I’m good with that too, I really don't mind. Thank you for your time in reviewing! 🙂
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Resolves #148275 by preventing name collisions in the
#[bench]macro.Previously, a user-defined function named "b" could not be benchmarked because
the macro-generated lambda identity collided with the same name. We now generate
the lambda ident as
__bench_<function_name>, ensuring it is always distinctfrom the user’s function.
Because the prefix is applied recursively (e.g. benchmarking
__bench_bproduces a lambda ident
__bench___bench_b), there is no possible functionname that can equal its corresponding lambda ident. This guarantees that
the user can safely bench a function of any valid name without risk of
identifier collision.