Auto merge of #46558 - arielb1:union-borrow-refactor, r=nikomatsakis

Clean up the MIR borrowck code

I want to avoid the new code to start with so much technical debt.

r? @nikomatsakis

Author: bors

src/librustc_mir/borrow_check/error_reporting.rs

@@ -0,0 +1,159 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Manages the dataflow bits required for borrowck.
+//!
+//! FIXME: this might be better as a "generic" fixed-point combinator,
+//! but is not as ugly as it is right now.
+
+use rustc::mir::{BasicBlock, Location};
+
+use dataflow::{MaybeInitializedLvals, MaybeUninitializedLvals};
+use dataflow::{EverInitializedLvals, MovingOutStatements};
+use dataflow::{Borrows, FlowAtLocation, FlowsAtLocation};
+use dataflow::move_paths::HasMoveData;
+use std::fmt;
+
+// (forced to be `pub` due to its use as an associated type below.)
+pub struct Flows<'b, 'gcx: 'tcx, 'tcx: 'b> {
+    pub borrows: FlowAtLocation<Borrows<'b, 'gcx, 'tcx>>,
+    pub inits: FlowAtLocation<MaybeInitializedLvals<'b, 'gcx, 'tcx>>,
+    pub uninits: FlowAtLocation<MaybeUninitializedLvals<'b, 'gcx, 'tcx>>,
+    pub move_outs: FlowAtLocation<MovingOutStatements<'b, 'gcx, 'tcx>>,
+    pub ever_inits: FlowAtLocation<EverInitializedLvals<'b, 'gcx, 'tcx>>,
+}
+
+impl<'b, 'gcx, 'tcx> Flows<'b, 'gcx, 'tcx> {
+    pub fn new(
+        borrows: FlowAtLocation<Borrows<'b, 'gcx, 'tcx>>,
+        inits: FlowAtLocation<MaybeInitializedLvals<'b, 'gcx, 'tcx>>,
+        uninits: FlowAtLocation<MaybeUninitializedLvals<'b, 'gcx, 'tcx>>,
+        move_outs: FlowAtLocation<MovingOutStatements<'b, 'gcx, 'tcx>>,
+        ever_inits: FlowAtLocation<EverInitializedLvals<'b, 'gcx, 'tcx>>,
+    ) -> Self {
+        Flows {
+            borrows,
+            inits,
+            uninits,
+            move_outs,
+            ever_inits,
+        }
+    }
+}
+
+macro_rules! each_flow {
+    ($this:ident, $meth:ident($arg:ident)) => {
+        FlowAtLocation::$meth(&mut $this.borrows, $arg);
+        FlowAtLocation::$meth(&mut $this.inits, $arg);
+        FlowAtLocation::$meth(&mut $this.uninits, $arg);
+        FlowAtLocation::$meth(&mut $this.move_outs, $arg);
+        FlowAtLocation::$meth(&mut $this.ever_inits, $arg);
+    }
+}
+
+impl<'b, 'gcx, 'tcx> FlowsAtLocation for Flows<'b, 'gcx, 'tcx> {
+    fn reset_to_entry_of(&mut self, bb: BasicBlock) {
+        each_flow!(self, reset_to_entry_of(bb));
+    }
+
+    fn reconstruct_statement_effect(&mut self, location: Location) {
+        each_flow!(self, reconstruct_statement_effect(location));
+    }
+
+    fn reconstruct_terminator_effect(&mut self, location: Location) {
+        each_flow!(self, reconstruct_terminator_effect(location));
+    }
+
+    fn apply_local_effect(&mut self, location: Location) {
+        each_flow!(self, apply_local_effect(location));
+    }
+}
+
+impl<'b, 'gcx, 'tcx> fmt::Display for Flows<'b, 'gcx, 'tcx> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut s = String::new();
+
+        s.push_str("borrows in effect: [");
+        let mut saw_one = false;
+        self.borrows.each_state_bit(|borrow| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let borrow_data = &self.borrows.operator().borrows()[borrow];
+            s.push_str(&format!("{}", borrow_data));
+        });
+        s.push_str("] ");
+
+        s.push_str("borrows generated: [");
+        let mut saw_one = false;
+        self.borrows.each_gen_bit(|borrow| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let borrow_data = &self.borrows.operator().borrows()[borrow];
+            s.push_str(&format!("{}", borrow_data));
+        });
+        s.push_str("] ");
+
+        s.push_str("inits: [");
+        let mut saw_one = false;
+        self.inits.each_state_bit(|mpi_init| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let move_path = &self.inits.operator().move_data().move_paths[mpi_init];
+            s.push_str(&format!("{}", move_path));
+        });
+        s.push_str("] ");
+
+        s.push_str("uninits: [");
+        let mut saw_one = false;
+        self.uninits.each_state_bit(|mpi_uninit| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let move_path =
+                &self.uninits.operator().move_data().move_paths[mpi_uninit];
+            s.push_str(&format!("{}", move_path));
+        });
+        s.push_str("] ");
+
+        s.push_str("move_out: [");
+        let mut saw_one = false;
+        self.move_outs.each_state_bit(|mpi_move_out| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let move_out = &self.move_outs.operator().move_data().moves[mpi_move_out];
+            s.push_str(&format!("{:?}", move_out));
+        });
+        s.push_str("] ");
+
+        s.push_str("ever_init: [");
+        let mut saw_one = false;
+        self.ever_inits.each_state_bit(|mpi_ever_init| {
+            if saw_one {
+                s.push_str(", ");
+            };
+            saw_one = true;
+            let ever_init =
+                &self.ever_inits.operator().move_data().inits[mpi_ever_init];
+            s.push_str(&format!("{:?}", ever_init));
+        });
+        s.push_str("]");
+
+        fmt::Display::fmt(&s, fmt)
+    }
+}