MIR borrow check (under debug flag) #43108
Commits on Aug 16, 2017
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Move borrowck error msg construction to module in
rustc_mir(for la……ter reuse by mir borrowck). post-rebase: Do not put "(Ast)" suffix in error msg unless passed `-Z borrowck-mir`. (But unconditionally include "(Mir)" suffix for mir-borrowck errors.)
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Refactor
trait BitDenotationto takeLocationinstead of `BasicBl……ock`/`usize` argument pairs.
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Added dataflow analysis for
Borrows.post-rebase: addressed review comment: rename `loc_map`/`location_map` and `rgn_map`/`region_map`. post-rebase: remove now unnecessary `mut` decl. post-rebase: address comments: bind iterator expr, and alpha-rename `loc`/`location` and `idx`/`index`.
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Migrated some code out of
dataflow::drop_flag_effectsand into its ……parent module. (This code is more general purpose than just supporting drop flag elaboration.)
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Move
DataFlowState::{each_bit,interpret_set}method definitions to ……parent module. Refactored `each_bit`, which traverses a `IdxSet`, so that the bulk of its implementation lives in `rustc_data_structures`.
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MIR based borrow check (opt-in).
One can either use `-Z borrowck-mir` or add the `#[rustc_mir_borrowck]` attribute to opt into MIR based borrow checking. Note that regardless of whether one opts in or not, AST-based borrow check will still run as well. The errors emitted from AST-based borrow check will include a "(Ast)" suffix in their error message, while the errors emitted from MIR-based borrow check will include a "(Mir)" suffix. post-rebase: removed check for intra-statement mutual conflict; replaced with assertion checking that at most one borrow is generated per statement. post-rebase: removed dead code: `IdxSet::pairs` and supporting stuff.
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Cleanup: Every
BitDenotationis aDataflowOperator, so build that…… in. Post-rebase: ariel confirmed `SetDiscriminant` should indeed be a mutate.
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Address review comment:
StatementKind::StorageDeadhas an effect (r……unning dtors) relevant to borrowck.
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Moved mir-borrowck pass down to where comments say it should be.
Added two fixmes: The `SimplifyBranches` pass cannot stay where it is, and `BorrowckMir` should be a query, not a pass. But I am going to leave those changes to a future PR.
