Doc comment custom MIR debuginfo. #117015
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| //! fn debuginfo(option: Option<&i32>) { | ||
| //! mir!( | ||
| //! debug option => option; | ||
| //! debug projection => *Field::<&i32>(Variant(option, 1), 0); |
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So what does this mean? There's no local "projection" so I'm confused by both the left-hand side and the right-hand side.
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This mean debuginfo name projection corresponds to the place (*((_1 as Some).0: &i32)).
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And what does that mean?^^ What's a "debuginfo name"?
If the intention is that this is only understandable for people that know our debuginfo system internals, then I guess it's fine. But as someone who has no idea at all about debuginfo, your explanation tells me nothing.
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I don't know the better terminology.
I by "debuginfo name", I mean the string you give to gdb when you want to print the variable.
MIR roughly represents debuginfo as a list of structs { Symbol, SourceScope, Place or Const }, stating "this name at at this point in code corresponds to this memory place".
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Ah so it's meant to be the name of the variable in the original source code?
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Yes.
Should we call it "Source code variable name"?
| //! #[custom_mir(dialect = "built")] | ||
| //! fn debuginfo(option: Option<&i32>) { | ||
| //! mir!( | ||
| //! debug option => option; |
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| //! debug option => option; | |
| //! debug plain_local => option; |
?
| //! - A debuginfo name can be given to a local using `debug my_name => contents;`. | ||
| //! For `contents`, we use the same syntax as operands, to support both places and constants. |
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| //! - A debuginfo name can be given to a local using `debug my_name => contents;`. | |
| //! For `contents`, we use the same syntax as operands, to support both places and constants. | |
| Debuginfo associates source code variable names (of variables that | |
| may not exist any more) with MIR expressions that indicate where | |
| the value of that variable is stored. The syntax to do so is: | |
| ``` | |
| debug source_var_name => expression; | |
| ``` | |
| For `expression`, we use the same syntax as operands, to support both places and constants. |
|
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☔ The latest upstream changes (presumably #119578) made this pull request unmergeable. Please resolve the merge conflicts. |
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@cjgillot what's the status of this PR? I think we have reached a consensus above for how to document this, it just needs to be implemented. :) |
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Ping from triage: I'm closing this due to inactivity because no commits have occurred in a year. Please reopen when you are ready to continue with this. @rustbot label: +S-inactive |
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I revived this PR at #133625 |
…compiler-errors custom MIR: add doc comment for debuginfo This is a revival of rust-lang#117015
…compiler-errors custom MIR: add doc comment for debuginfo This is a revival of rust-lang#117015
Rollup merge of rust-lang#133625 - RalfJung:custom-mir-debug-info, r=compiler-errors custom MIR: add doc comment for debuginfo This is a revival of rust-lang#117015
r? @RalfJung
Asked in https://github.com/rust-lang/rust/pull/115540/files#r1318762354