Clean up operator representations #134552
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`AssocOp::AssignOp` contains a `BinOpToken`. `ExprKind::AssignOp` contains a `BinOpKind`. Given that `AssocOp` is basically a cut-down version of `ExprKind`, it makes sense to make `AssocOp` more like `ExprKind`. Especially given that `AssocOp` and `BinOpKind` use semantic operation names (e.g. `Mul`, `Div`), but `BinOpToken` uses syntactic names (e.g. `Star`, `Slash`). This results in more concise code, and removes the need for various conversions. (Note that the removed functions `hirbinop2assignop` and `astbinop2assignop` are semantically identical, because `hir::BinOp` is just a synonum for `ast::BinOp`!) The only downside to this is that it allows the possibility of some nonsensical combinations, such as `AssocOp::AssignOp(BinOpKind::Lt)`. But `ExprKind::AssignOp` already has that problem. The problem can be fixed for both types in the future with some effort, by introducing an `AssignOpKind` type.
It mirrors `ExprKind::Binary`, and contains a `BinOpKind`. This makes `AssocOp` more like `ExprKind`. Note that the variants removed from `AssocOp` are all named differently to `BinOpToken`, e.g. `Multiply` instead of `Mul`, so that's an inconsistency removed. The commit adds `precedence` and `fixity` methods to `BinOpKind`, and calls them from the corresponding methods in `AssocOp`. This avoids the need to create an `AssocOp` from a `BinOpKind` in a bunch of places, and `AssocOp::from_ast_binop` is removed. `AssocOp::to_ast_binop` is also no longer needed. Overall things are shorter and nicer.
It makes `AssocOp` more similar to `ExprKind` and makes things a little simpler. And the semantic names make more sense here than the syntactic names.
To match `ExprKind::Cast`, and because a semantic name makes more sense here than a syntactic name.
`BinOpToken` is badly named, because it only covers the assignable
binary ops and excludes comparisons and `&&`/`||`. Its use in
`ast::TokenKind` does allow a small amount of code sharing, but it's a
clumsy factoring.
This commit removes `ast::TokenKind::BinOp{,Eq}`, replacing each one
with 10 individual variants. This makes `ast::TokenKind` more similar to
`rustc_lexer::TokenKind`, which has individual variants for all
operators.
Although the number of lines of code increases, the number of chars
decreases due to the frequent use of shorter names like `token::Plus`
instead of `token::BinOp(BinOpToken::Plus)`.
For consistency with `rustc_lexer::TokenKind::Bang`, and because other `ast::TokenKind` variants generally have syntactic names instead of semantic names (e.g. `Star` and `DotDot` instead of `Mul` and `Range`).
First, move the `lang_item_for_op` call from the top of
`lookup_op_method`'s body to its callsites. It makes those callsites a
little more verbose, but also means `lookup_op_method` no longer cares
whether it's handling a binop or unop. This lets us remove `Op` and
split `lang_item_for_op` into `lang_item_for_{bin,un}op`, which is a
little simpler.
This change is a prerequisite for adding the `ast::AssignOpKind` type in
a subsequent commit.
Because it's nice to avoid passing in unnecessary data.
In the AST, currently we use `BinOpKind` within `ExprKind::AssignOp` and `AssocOp::AssignOp`, even though this allows some nonsensical combinations. E.g. there is no `&&=` operator. Likewise for HIR and THIR. This commit introduces `AssignOpKind` which only includes the ten assignable operators, and uses it in `ExprKind::AssignOp` and `AssocOp::AssignOp`. (And does similar things for `hir::ExprKind` and `thir::ExprKind`.) This avoids the possibility of nonsensical combinations, as seen by the removal of the `bug!` case in `lang_item_for_binop`. The commit is mostly plumbing, including: - Adds an `impl From<AssignOpKind> for BinOpKind` (AST) and `impl From<AssignOp> for BinOp` (MIR/THIR). - `BinOpCategory` can now be created from both `BinOpKind` and `AssignOpKind`. - Replaces the `IsAssign` type with `Op`, which has more information and a few methods. - `suggest_swapping_lhs_and_rhs`: moves the condition to the call site, it's easier that way. - `check_expr_inner`: had to factor out some code into a separate method. I'm on the fence about whether avoiding the nonsensical combinations is worth the extra code.
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☔ The latest upstream changes (presumably #136209) made this pull request unmergeable. Please resolve the merge conflicts. |
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Draft code implementing MCP 831.
r? @ghost