Deduplicate operand creation between scalars, non-scalars and string patterns
just something that felt duplicated and would make pattern type handling a bit more roundabout.
Fix ICE-133117: multiple never-pattern arm doesn't have false_edge_start_block
Fixes#133117 , and close fixes#133063 , fixes#130779
In order to fix ICE-133117, at first I needed to tackle to ICE-133063 (this fixed 130779 as well).
### ICE-133063 and ICE-130779
This ICE is caused by those steps:
1. An arm has or-pattern, and all of the sub-candidates are never-pattern
2. In that case, all sub-candidates are removed in remove_never_subcandidates(). So the arm (candidate) has no sub-candidate.
3. In the current implementation, if there is no sub-candidate, the function assigns `pre_binding_block` into the candidate ([here](https://github.com/rust-lang/rust/blob/master/compiler/rustc_mir_build/src/builder/matches/mod.rs#L2002-L2004)). However, otherwise_block should be assigned to the candidate as well, because the otherwise_block is unwrapped in multiple place (like in lower_match_tree()). As a result, it causes the panic.
I simply added the same block as pre_binding_block into otherwise_block, but I'm wondering if there is a better block to assign to otherwise_block (is it ok to assign the same block into pre_binding and otherwise?)
### ICE-133117
This is caused by those steps:
1. There are two arms, both are or-pattern and each has one match-pair (in the test code, both are `(!|!)`), and the second arm has a guard.
2. In match_candidate() for the first arm, it expands the second arm’s sub-candidates as well ([here](https://github.com/rust-lang/rust/blob/master/compiler/rustc_mir_build/src/builder/matches/mod.rs#L1800-L1805)). As a result, the root candidate of the second arm is not evaluated/modified in match_candidate(). So a false_edge_start_block is not assigned to the candidate.
3. merge_trivial_subcandidates() is called against the candidate for the second arm. It just returns immediately because the candidate has a guard. So a flase_edge_start_block is not assigned to the candidate also in this function.
4. remove_never_subcandidates() is called against the candidate. Since all sub-candidates are never-pattern. they are removed.
5. In lower_match_tree(), since there is no sub-candidate for the candidate, the candidate itself is evaluated in visit_leave_rev ([here](https://github.com/rust-lang/rust/blob/master/compiler/rustc_mir_build/src/builder/matches/mod.rs#L1532)). Because the candidate has no false_edge_start_block, it causes the panic.
So I modified the order of if blocks in merge_trivial_subcandidates() to assign a false_edge_start_block if the candidate doesn't have.
The candidate shouldn't have false_edge_start_block if it has sub candidates.
In remove_never_subcandidates(), the false_edge_start_block from the first sub candidte is assigned to a value and the value is later used if all sub candidates are removed and candidate doesn't have false_edge_start_block.
In merge_trivial_subcandidates, I leave the if block which assign a false_edge_start_block into the candidate as before I put this commit since compile panics.
Signed-off-by: Shunpoco <tkngsnsk313320@gmail.com>
If all subcandidates have never-pattern, we should assign false_edge_start_block to the parent candidate
if it doesn't have. merge_trivial_subcandidates does so, but if the candidate has guard it returns before the assignment.
Signed-off-by: Shunpoco <tkngsnsk313320@gmail.com>
If all subcandidates have never-pattern, the parent candidate should have otherwise_block
because some methods expect the candidate has the block.
Signed-off-by: Shunpoco <tkngsnsk313320@gmail.com>
Make sure we handle `backwards_incompatible_lint` drops appropriately in drop elaboration
In #131326, a new kind of scheduled drop (`drop_kind: DropKind::Value` + `backwards_incompatible_lint: true`) was added so that we could insert a new kind of no-op MIR statement (`backward incompatible drop`) for linting purposes.
These drops were intended to have *no side-effects*, but drop elaboration code forgot to handle these drops specially and they were handled otherwise as normal drops in most of the code. This ends up being **unsound** since we insert more than one drop call for some values, which means that `Drop::drop` could be called more than once.
This PR fixes this by splitting out the `DropKind::ForLint` and adjusting the code. I'm not totally certain if all of the places I've adjusted are either reachable or correct, but I'm pretty certain that it's *more* correct than it was previously.
cc `@dingxiangfei2009`
r? nikomatsakis
Fixes#134482
Do not do if ! else, use unnegated cond and swap the branches instead
I'm tidying up my ergonomic ref counting PR and I'm going to make some small, simple and unrelated changes outside that PR, so the main PR sticks more straight to the point.
`rustc_span::symbol` defines some things that are re-exported from
`rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some
closely related things such as `Ident` and `kw`. So you can do `use
rustc_span::{Symbol, sym}` but you have to do `use
rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good
reason.
This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`,
and changes many `rustc_span::symbol::` qualifiers in `compiler/` to
`rustc_span::`. This is a 200+ net line of code reduction, mostly
because many files with two `use rustc_span` items can be reduced to
one.
León Orell Valerian Liehr