auto merge of #14318 : zwarich/rust/check-loans-refactor, r=nikomatsakis

I tried to split up the less mechanical changes into separate commits so they are easier to review. One thing I'm not quite sure of is whether `MoveReason` should just be replaced with `move_data::MoveKind`.

Author: bors

src/librustc/middle/borrowck/check_loans.rs

@@ -45,10 +45,15 @@ pub fn gather_move_from_expr(bccx: &BorrowckCtxt,
                              move_data: &MoveData,
                              move_error_collector: &MoveErrorCollector,
                              move_expr_id: ast::NodeId,
-                             cmt: mc::cmt) {
+                             cmt: mc::cmt,
+                             move_reason: euv::MoveReason) {
+    let kind = match move_reason {
+        euv::DirectRefMove | euv::PatBindingMove => MoveExpr,
+        euv::CaptureMove => Captured
+    };
     let move_info = GatherMoveInfo {
         id: move_expr_id,
-        kind: MoveExpr,
+        kind: kind,
         cmt: cmt,
         span_path_opt: None,
     };

src/librustc/middle/borrowck/gather_loans/gather_moves.rs

@@ -75,13 +75,13 @@ impl<'a> euv::Delegate for GatherLoanCtxt<'a> {
                consume_id, cmt.repr(self.tcx()), mode);
 
         match mode {
-            euv::Copy => { return; }
-            euv::Move => { }
+            euv::Move(move_reason) => {
+                gather_moves::gather_move_from_expr(
+                    self.bccx, &self.move_data, &self.move_error_collector,
+                    consume_id, cmt, move_reason);
+            }
+            euv::Copy => { }
         }
-
-        gather_moves::gather_move_from_expr(
-            self.bccx, &self.move_data, &self.move_error_collector,
-            consume_id, cmt);
     }
 
     fn consume_pat(&mut self,
@@ -95,7 +95,7 @@ impl<'a> euv::Delegate for GatherLoanCtxt<'a> {
 
         match mode {
             euv::Copy => { return; }
-            euv::Move => { }
+            euv::Move(_) => { }
         }
 
         gather_moves::gather_move_from_pat(

src/librustc/middle/borrowck/gather_loans/mod.rs

@@ -142,7 +142,7 @@ fn borrowck_fn(this: &mut BorrowckCtxt,
                                                       body);
 
     check_loans::check_loans(this, &loan_dfcx, flowed_moves,
-                             all_loans.as_slice(), body);
+                             all_loans.as_slice(), decl, body);
 
     visit::walk_fn(this, fk, decl, body, sp, ());
 }

src/librustc/middle/borrowck/mod.rs

@@ -115,6 +115,7 @@ pub struct MovePath {
     pub next_sibling: MovePathIndex,
 }
 
+#[deriving(PartialEq)]
 pub enum MoveKind {
     Declared,   // When declared, variables start out "moved".
     MoveExpr,   // Expression or binding that moves a variable
@@ -356,7 +357,7 @@ impl MoveData {
         let path_index = self.move_path(tcx, lp.clone());
 
         match mode {
-            euv::JustWrite => {
+            euv::Init | euv::JustWrite => {
                 self.assignee_ids.borrow_mut().insert(assignee_id);
             }
             euv::WriteAndRead => { }
@@ -537,6 +538,28 @@ impl<'a> FlowedMoveData<'a> {
         })
     }
 
+    pub fn kind_of_move_of_path(&self,
+                                id: ast::NodeId,
+                                loan_path: &Rc<LoanPath>)
+                                -> Option<MoveKind> {
+        //! Returns the kind of a move of `loan_path` by `id`, if one exists.
+
+        let mut ret = None;
+        for loan_path_index in self.move_data.path_map.borrow().find(&*loan_path).iter() {
+            self.dfcx_moves.each_gen_bit_frozen(id, |move_index| {
+                let move = self.move_data.moves.borrow();
+                let move = move.get(move_index);
+                if move.path == **loan_path_index {
+                    ret = Some(move.kind);
+                    false
+                } else {
+                    true
+                }
+            });
+        }
+        ret
+    }
+
     pub fn each_move_of(&self,
                         id: ast::NodeId,
                         loan_path: &Rc<LoanPath>,

src/librustc/middle/borrowck/move_data.rs

@@ -80,12 +80,20 @@ pub enum LoanCause {
 
 #[deriving(PartialEq,Show)]
 pub enum ConsumeMode {
-    Copy,    // reference to x where x has a type that copies
-    Move,    // reference to x where x has a type that moves
+    Copy,                // reference to x where x has a type that copies
+    Move(MoveReason),    // reference to x where x has a type that moves
+}
+
+#[deriving(PartialEq,Show)]
+pub enum MoveReason {
+    DirectRefMove,
+    PatBindingMove,
+    CaptureMove,
 }
 
 #[deriving(PartialEq,Show)]
 pub enum MutateMode {
+    Init,
     JustWrite,    // x = y
     WriteAndRead, // x += y
 }
@@ -160,7 +168,7 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
                         consume_id: ast::NodeId,
                         consume_span: Span,
                         cmt: mc::cmt) {
-        let mode = copy_or_move(self.tcx(), cmt.ty);
+        let mode = copy_or_move(self.tcx(), cmt.ty, DirectRefMove);
         self.delegate.consume(consume_id, consume_span, cmt, mode);
     }
 
@@ -712,7 +720,7 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
                 let def = def_map.borrow().get_copy(&pat.id);
                 match mc.cat_def(pat.id, pat.span, pat_ty, def) {
                     Ok(binding_cmt) => {
-                        delegate.mutate(pat.id, pat.span, binding_cmt, JustWrite);
+                        delegate.mutate(pat.id, pat.span, binding_cmt, Init);
                     }
                     Err(_) => { }
                 }
@@ -728,7 +736,7 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
                                              r, bk, RefBinding);
                     }
                     ast::PatIdent(ast::BindByValue(_), _, _) => {
-                        let mode = copy_or_move(typer.tcx(), cmt_pat.ty);
+                        let mode = copy_or_move(typer.tcx(), cmt_pat.ty, PatBindingMove);
                         delegate.consume_pat(pat, cmt_pat, mode);
                     }
                     _ => {
@@ -834,7 +842,8 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
             let cmt_var = return_if_err!(self.cat_captured_var(closure_expr.id,
                                                                closure_expr.span,
                                                                freevar.def));
-            self.delegate_consume(closure_expr.id, freevar.span, cmt_var);
+            let mode = copy_or_move(self.tcx(), cmt_var.ty, CaptureMove);
+            self.delegate.consume(closure_expr.id, freevar.span, cmt_var, mode);
         }
     }
 
@@ -851,7 +860,7 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
     }
 }
 
-fn copy_or_move(tcx: &ty::ctxt, ty: ty::t) -> ConsumeMode {
-    if ty::type_moves_by_default(tcx, ty) { Move } else { Copy }
+fn copy_or_move(tcx: &ty::ctxt, ty: ty::t, move_reason: MoveReason) -> ConsumeMode {
+    if ty::type_moves_by_default(tcx, ty) { Move(move_reason) } else { Copy }
 }
 

src/librustc/middle/expr_use_visitor.rs

@@ -390,12 +390,10 @@ impl<'t,TYPER:Typer> MemCategorizationContext<'t,TYPER> {
             Some(adjustment) => {
                 match *adjustment {
                     ty::AutoObject(..) => {
-                        // Implicity casts a concrete object to trait object
-                        // so just patch up the type
+                        // Implicity cast a concrete object to trait object.
+                        // Result is an rvalue.
                         let expr_ty = if_ok!(self.expr_ty_adjusted(expr));
-                        let mut expr_cmt = (*if_ok!(self.cat_expr_unadjusted(expr))).clone();
-                        expr_cmt.ty = expr_ty;
-                        Ok(Rc::new(expr_cmt))
+                        Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
                     }
 
                     ty::AutoAddEnv(..) => {

src/librustc/middle/mem_categorization.rs

@@ -0,0 +1,124 @@
+// Copyright 2014 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.
+
+struct A { a: int, b: Box<int> }
+
+fn borrow<T>(_: &T) { }
+
+fn use_after_move() {
+    let x = A { a: 1, b: box 2 };
+    drop(x.b);
+    drop(*x.b); //~ ERROR use of partially moved value: `*x.b`
+}
+
+fn use_after_fu_move() {
+    let x = A { a: 1, b: box 2 };
+    let y = A { a: 3, .. x };
+    drop(*x.b); //~ ERROR use of partially moved value: `*x.b`
+}
+
+fn borrow_after_move() {
+    let x = A { a: 1, b: box 2 };
+    drop(x.b);
+    borrow(&x.b); //~ ERROR use of moved value: `x.b`
+}
+
+fn borrow_after_fu_move() {
+    let x = A { a: 1, b: box 2 };
+    let _y = A { a: 3, .. x };
+    borrow(&x.b); //~ ERROR use of moved value: `x.b`
+}
+
+fn move_after_borrow() {
+    let x = A { a: 1, b: box 2 };
+    let y = &x.b;
+    drop(x.b); //~ ERROR cannot move out of `x.b` because it is borrowed
+    borrow(&*y);
+}
+
+fn fu_move_after_borrow() {
+    let x = A { a: 1, b: box 2 };
+    let y = &x.b;
+    let _z = A { a: 3, .. x }; //~ ERROR cannot move out of `x.b` because it is borrowed
+    borrow(&*y);
+}
+
+fn mut_borrow_after_mut_borrow() {
+    let mut x = A { a: 1, b: box 2 };
+    let y = &mut x.a;
+    let z = &mut x.a; //~ ERROR cannot borrow `x.a` as mutable more than once at a time
+    drop(*y);
+    drop(*z);
+}
+
+fn move_after_move() {
+    let x = A { a: 1, b: box 2 };
+    drop(x.b);
+    drop(x.b);  //~ ERROR use of moved value: `x.b`
+}
+
+fn move_after_fu_move() {
+    let x = A { a: 1, b: box 2 };
+    let _y = A { a: 3, .. x };
+    drop(x.b);  //~ ERROR use of moved value: `x.b`
+}
+
+fn fu_move_after_move() {
+    let x = A { a: 1, b: box 2 };
+    drop(x.b);
+    let _z = A { a: 3, .. x };  //~ ERROR use of moved value: `x.b`
+}
+
+fn fu_move_after_fu_move() {
+    let x = A { a: 1, b: box 2 };
+    let _y = A { a: 3, .. x };
+    let _z = A { a: 4, .. x };  //~ ERROR use of moved value: `x.b`
+}
+
+// The following functions aren't yet accepted, but they should be.
+
+fn use_after_field_assign_after_uninit() {
+    let mut x: A;
+    x.a = 1;
+    drop(x.a); //~ ERROR use of possibly uninitialized variable: `x.a`
+}
+
+fn borrow_after_field_assign_after_uninit() {
+    let mut x: A;
+    x.a = 1;
+    borrow(&x.a); //~ ERROR use of possibly uninitialized variable: `x.a`
+}
+
+fn move_after_field_assign_after_uninit() {
+    let mut x: A;
+    x.b = box 1;
+    drop(x.b); //~ ERROR use of possibly uninitialized variable: `x.b`
+}
+
+fn main() {
+    use_after_move();
+    use_after_fu_move();
+
+    borrow_after_move();
+    borrow_after_fu_move();
+    move_after_borrow();
+    fu_move_after_borrow();
+    mut_borrow_after_mut_borrow();
+
+    move_after_move();
+    move_after_fu_move();
+    fu_move_after_move();
+    fu_move_after_fu_move();
+
+    use_after_field_assign_after_uninit();
+    borrow_after_field_assign_after_uninit();
+    move_after_field_assign_after_uninit();
+}
+

src/test/compile-fail/borrowck-field-sensitivity.rs

@@ -16,6 +16,6 @@ struct point {
 
 fn main() {
     let mut origin: point;
-    origin = point {x: 10,.. origin}; //~ ERROR use of possibly uninitialized variable: `origin`
+    origin = point {x: 10,.. origin}; //~ ERROR use of possibly uninitialized variable: `origin.y`
     origin.clone();
 }

src/test/compile-fail/borrowck-init-in-fru.rs

@@ -0,0 +1,64 @@
+// Copyright 2014 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.
+
+use std::task;
+
+fn borrow<T>(_: &T) { }
+
+fn different_vars_after_borrows() {
+    let x1 = box 1;
+    let p1 = &x1;
+    let x2 = box 2;
+    let p2 = &x2;
+    task::spawn(proc() {
+        drop(x1); //~ ERROR cannot move `x1` into closure because it is borrowed
+        drop(x2); //~ ERROR cannot move `x2` into closure because it is borrowed
+    });
+    borrow(&*p1);
+    borrow(&*p2);
+}
+
+fn different_vars_after_moves() {
+    let x1 = box 1;
+    drop(x1);
+    let x2 = box 2;
+    drop(x2);
+    task::spawn(proc() {
+        drop(x1); //~ ERROR capture of moved value: `x1`
+        drop(x2); //~ ERROR capture of moved value: `x2`
+    });
+}
+
+fn same_var_after_borrow() {
+    let x = box 1;
+    let p = &x;
+    task::spawn(proc() {
+        drop(x); //~ ERROR cannot move `x` into closure because it is borrowed
+        drop(x); //~ ERROR use of moved value: `x`
+    });
+    borrow(&*p);
+}
+
+fn same_var_after_move() {
+    let x = box 1;
+    drop(x);
+    task::spawn(proc() {
+        drop(x); //~ ERROR capture of moved value: `x`
+        drop(x); //~ ERROR use of moved value: `x`
+    });
+}
+
+fn main() {
+    different_vars_after_borrows();
+    different_vars_after_moves();
+    same_var_after_borrow();
+    same_var_after_move();
+}
+

src/test/compile-fail/borrowck-multiple-captures.rs

@@ -13,6 +13,6 @@ extern crate debug;
 fn main() {
     let x = box 5;
     let y = x;
-    println!("{:?}", *x); //~ ERROR use of moved value: `x`
+    println!("{:?}", *x); //~ ERROR use of partially moved value: `*x`
     y.clone();
 }