mir-borrowck: Factorize error message for cannot_assign_static() between AST and MIR borrowck

Author: zilbuz

Diff for: src/librustc_borrowck/borrowck/mod.rs

@@ -759,11 +759,7 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
 
                 let mut db = match err.cause {
                     MutabilityViolation => {
-                        struct_span_err!(self.tcx.sess,
-                                         error_span,
-                                         E0594,
-                                         "cannot assign to {}",
-                                         descr)
+                        self.cannot_assign(error_span, &descr, Origin::Ast)
                     }
                     BorrowViolation(euv::ClosureCapture(_)) => {
                         struct_span_err!(self.tcx.sess, error_span, E0595,

Diff for: src/librustc_borrowck/diagnostics.rs

@@ -742,6 +742,5 @@ b.resume();
 
 register_diagnostics! {
 //    E0385, // {} in an aliasable location
-    E0594, // cannot assign to {}
     E0598, // lifetime of {} is too short to guarantee its contents can be...
 }

Diff for: src/librustc_mir/borrow_check.rs

@@ -1010,7 +1010,6 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
     fn report_assignment_to_static(&mut self, _context: Context, (lvalue, span): (&Lvalue, Span)) {
         let mut err = self.tcx.cannot_assign_static(
             span, &self.describe_lvalue(lvalue), Origin::Mir);
-        // FIXME: add span labels for borrow and assignment points
         err.emit();
     }
 }

Diff for: src/librustc_mir/diagnostics.rs

@@ -1005,5 +1005,6 @@ register_diagnostics! {
     E0493, // destructors cannot be evaluated at compile-time
     E0524, // two closures require unique access to `..` at the same time
     E0526, // shuffle indices are not constant
+    E0594, // cannot assign to {}
     E0625, // thread-local statics cannot be accessed at compile-time
 }

Diff for: src/librustc_mir/util/borrowck_errors.rs

@@ -179,11 +179,17 @@ pub trait BorrowckErrors {
                          desc, OGN=o)
     }
 
+    fn cannot_assign(&self, span: Span, desc: &str, o: Origin) -> DiagnosticBuilder
+    {
+        struct_span_err!(self, span, E0594,
+                         "cannot assign to {}{OGN}",
+                         desc, OGN=o)
+    }
+
     fn cannot_assign_static(&self, span: Span, desc: &str, o: Origin)
                             -> DiagnosticBuilder
     {
-        self.struct_span_err(span, &format!("cannot assign to immutable static item {}{OGN}",
-                                            desc, OGN=o))
+        self.cannot_assign(span, &format!("immutable static item `{}`", desc), o)
     }
 }
 

Diff for: src/test/compile-fail/E0594.rs

@@ -0,0 +1,20 @@
+// 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.
+
+// revisions: ast mir
+//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
+static NUM: i32 = 18;
+
+fn main() {
+    NUM = 20; //[ast]~ ERROR E0594
+              //[mir]~^ ERROR cannot assign to immutable static item (Ast)
+              //[mir]~| ERROR cannot assign to immutable static item `NUM` (Mir)
+}

Diff for: src/test/compile-fail/borrowck/borrowck-assign-to-constants.rs

@@ -8,9 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// revisions: ast mir
+//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
 static foo: isize = 5;
 
 fn main() {
     // assigning to various global constants
-    foo = 6; //~ ERROR cannot assign to immutable static item
+    foo = 6; //[ast]~ ERROR cannot assign to immutable static item
+             //[mir]~^ ERROR cannot assign to immutable static item (Ast)
+             //[mir]~| ERROR cannot assign to immutable static item `foo` (Mir)
 }

Diff for: src/test/compile-fail/borrowck/borrowck-overloaded-index-ref-index.rs

@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// revisions: ast mir
+//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
 use std::ops::{Index, IndexMut};
 
 struct Foo {
@@ -57,12 +60,18 @@ fn main() {
     let mut s = "hello".to_string();
     let rs = &mut s;
     println!("{}", f[&s]);
-    //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    //[ast]~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    //[mir]~^^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable (Ast)
+    //[mir]~| ERROR cannot borrow `s` as immutable because it is also borrowed as mutable (Mir)
     f[&s] = 10;
-    //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    //[ast]~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
+    //[mir]~^^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable (Ast)
+    //[mir]~| ERROR cannot borrow `s` as immutable because it is also borrowed as mutable (Mir)
     let s = Bar {
         x: 1,
     };
     s[2] = 20;
-    //~^ ERROR cannot assign to immutable indexed content
+    //[ast]~^ ERROR cannot assign to immutable indexed content
+    //[mir]~^^ ERROR cannot assign to immutable indexed content
+    // FIXME Error for MIR
 }

Diff for: src/test/compile-fail/issue-5500-1.rs

@@ -8,13 +8,18 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// revisions: ast mir
+//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
 struct TrieMapIterator<'a> {
     node: &'a usize
 }
 
 fn main() {
     let a = 5;
     let _iter = TrieMapIterator{node: &a};
-    _iter.node = & //~ ERROR cannot assign to immutable field
+    _iter.node = & //[ast]~ ERROR cannot assign to immutable field
+                   //[mir]~^ ERROR cannot assign to immutable field `_iter.node` (Ast)
+                   // FIXME Error for MIR
     panic!()
 }