Auto merge of #48082 - jseyfried:improve_struct_field_hygiene, r=petrochenkov

macros: improve struct constructor field hygiene, fix span bug

Fixes #47311.
r? @nrc

Author: bors

Diff for: src/librustc_privacy/lib.rs

@@ -34,6 +34,7 @@ use rustc::util::nodemap::NodeSet;
 use syntax::ast::{self, CRATE_NODE_ID, Ident};
 use syntax::symbol::keywords;
 use syntax_pos::Span;
+use syntax_pos::hygiene::SyntaxContext;
 
 use std::cmp;
 use std::mem::replace;
@@ -491,9 +492,13 @@ struct NamePrivacyVisitor<'a, 'tcx: 'a> {
 }
 
 impl<'a, 'tcx> NamePrivacyVisitor<'a, 'tcx> {
-    // Checks that a field is accessible.
-    fn check_field(&mut self, span: Span, def: &'tcx ty::AdtDef, field: &'tcx ty::FieldDef) {
-        let ident = Ident { ctxt: span.ctxt().modern(), ..keywords::Invalid.ident() };
+    // Checks that a field in a struct constructor (expression or pattern) is accessible.
+    fn check_field(&mut self,
+                   use_ctxt: SyntaxContext, // Syntax context of the field name at the use site
+                   span: Span, // Span of the field pattern, e.g. `x: 0`
+                   def: &'tcx ty::AdtDef, // Definition of the struct or enum
+                   field: &'tcx ty::FieldDef) { // Definition of the field
+        let ident = Ident { ctxt: use_ctxt.modern(), ..keywords::Invalid.ident() };
         let def_id = self.tcx.adjust_ident(ident, def.did, self.current_item).1;
         if !def.is_enum() && !field.vis.is_accessible_from(def_id, self.tcx) {
             struct_span_err!(self.tcx.sess, span, E0451, "field `{}` of {} `{}` is private",
@@ -566,12 +571,17 @@ impl<'a, 'tcx> Visitor<'tcx> for NamePrivacyVisitor<'a, 'tcx> {
                     // unmentioned fields, just check them all.
                     for variant_field in &variant.fields {
                         let field = fields.iter().find(|f| f.name.node == variant_field.name);
-                        let span = if let Some(f) = field { f.span } else { base.span };
-                        self.check_field(span, adt, variant_field);
+                        let (use_ctxt, span) = match field {
+                            Some(field) => (field.name.node.to_ident().ctxt, field.span),
+                            None => (base.span.ctxt(), base.span),
+                        };
+                        self.check_field(use_ctxt, span, adt, variant_field);
                     }
                 } else {
                     for field in fields {
-                        self.check_field(field.span, adt, variant.field_named(field.name.node));
+                        let use_ctxt = field.name.node.to_ident().ctxt;
+                        let field_def = variant.field_named(field.name.node);
+                        self.check_field(use_ctxt, field.span, adt, field_def);
                     }
                 }
             }
@@ -588,7 +598,9 @@ impl<'a, 'tcx> Visitor<'tcx> for NamePrivacyVisitor<'a, 'tcx> {
                 let adt = self.tables.pat_ty(pat).ty_adt_def().unwrap();
                 let variant = adt.variant_of_def(def);
                 for field in fields {
-                    self.check_field(field.span, adt, variant.field_named(field.node.name));
+                    let use_ctxt = field.node.name.to_ident().ctxt;
+                    let field_def = variant.field_named(field.node.name);
+                    self.check_field(use_ctxt, field.span, adt, field_def);
                 }
             }
             _ => {}

Diff for: src/libsyntax/parse/parser.rs

@@ -2125,8 +2125,8 @@ impl<'a> Parser<'a> {
         // Check if a colon exists one ahead. This means we're parsing a fieldname.
         let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
             let fieldname = self.parse_field_name()?;
-            self.bump();
             hi = self.prev_span;
+            self.bump();
             (fieldname, self.parse_expr()?, false)
         } else {
             let fieldname = self.parse_ident_common(false)?;

Diff for: src/test/run-pass/hygiene/issue-47311.rs

@@ -0,0 +1,26 @@
+// Copyright 2018 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.
+
+// ignore-pretty pretty-printing is unhygienic
+
+#![feature(decl_macro)]
+#![allow(unused)]
+
+macro m($S:ident, $x:ident) {
+    $S { $x: 0 }
+}
+
+mod foo {
+    struct S { x: i32 }
+
+    fn f() { ::m!(S, x); }
+}
+
+fn main() {}

Diff for: src/test/ui/did_you_mean/issue-42599_available_fields_note.stderr

@@ -2,13 +2,13 @@ error[E0560]: struct `submodule::Demo` has no field named `inocently_mispellable
   --> $DIR/issue-42599_available_fields_note.rs:26:39
    |
 26 |             Self { secret_integer: 2, inocently_mispellable: () }
-   |                                       ^^^^^^^^^^^^^^^^^^^^^^ field does not exist - did you mean `innocently_misspellable`?
+   |                                       ^^^^^^^^^^^^^^^^^^^^^ field does not exist - did you mean `innocently_misspellable`?
 
 error[E0560]: struct `submodule::Demo` has no field named `egregiously_nonexistent_field`
   --> $DIR/issue-42599_available_fields_note.rs:31:39
    |
 31 |             Self { secret_integer: 3, egregiously_nonexistent_field: () }
-   |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `submodule::Demo` does not have this field
+   |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `submodule::Demo` does not have this field
    |
    = note: available fields are: `favorite_integer`, `secret_integer`, `innocently_misspellable`, `another_field`, `yet_another_field` ... and 2 others
 

Diff for: src/test/ui/error-codes/E0062.stderr

@@ -4,7 +4,7 @@ error[E0062]: field `x` specified more than once
 17 |         x: 0,
    |         ---- first use of `x`
 18 |         x: 0,
-   |         ^^ used more than once
+   |         ^ used more than once
 
 error: aborting due to previous error
 

Diff for: src/test/ui/error-codes/E0559.stderr

@@ -2,7 +2,7 @@ error[E0559]: variant `Field::Fool` has no field named `joke`
   --> $DIR/E0559.rs:16:27
    |
 16 |     let s = Field::Fool { joke: 0 };
-   |                           ^^^^^ `Field::Fool` does not have this field
+   |                           ^^^^ `Field::Fool` does not have this field
    |
    = note: available fields are: `x`
 

Diff for: src/test/ui/error-codes/E0560.stderr

@@ -2,7 +2,7 @@ error[E0560]: struct `Simba` has no field named `father`
   --> $DIR/E0560.rs:16:32
    |
 16 |     let s = Simba { mother: 1, father: 0 };
-   |                                ^^^^^^^ `Simba` does not have this field
+   |                                ^^^^^^ `Simba` does not have this field
    |
    = note: available fields are: `mother`
 

Diff for: src/test/ui/issue-19922.stderr

@@ -2,7 +2,7 @@ error[E0559]: variant `Homura::Akemi` has no field named `kaname`
   --> $DIR/issue-19922.rs:16:34
    |
 16 |     let homura = Homura::Akemi { kaname: () };
-   |                                  ^^^^^^^ `Homura::Akemi` does not have this field
+   |                                  ^^^^^^ `Homura::Akemi` does not have this field
    |
    = note: available fields are: `madoka`
 

Diff for: src/test/ui/numeric-fields.stderr

@@ -2,7 +2,7 @@ error[E0560]: struct `S` has no field named `0b1`
   --> $DIR/numeric-fields.rs:14:15
    |
 14 |     let s = S{0b1: 10, 0: 11};
-   |               ^^^^ `S` does not have this field
+   |               ^^^ `S` does not have this field
    |
    = note: available fields are: `0`, `1`
 

Diff for: src/test/ui/struct-fields-hints-no-dupe.stderr

@@ -2,7 +2,7 @@ error[E0560]: struct `A` has no field named `bar`
   --> $DIR/struct-fields-hints-no-dupe.rs:20:9
    |
 20 |         bar : 42,
-   |         ^^^^^ field does not exist - did you mean `barr`?
+   |         ^^^ field does not exist - did you mean `barr`?
 
 error: aborting due to previous error
 

Diff for: src/test/ui/struct-fields-hints.stderr

@@ -2,7 +2,7 @@ error[E0560]: struct `A` has no field named `bar`
   --> $DIR/struct-fields-hints.rs:20:9
    |
 20 |         bar : 42,
-   |         ^^^^^ field does not exist - did you mean `car`?
+   |         ^^^ field does not exist - did you mean `car`?
 
 error: aborting due to previous error
 

Diff for: src/test/ui/struct-fields-too-many.stderr

@@ -2,7 +2,7 @@ error[E0560]: struct `BuildData` has no field named `bar`
   --> $DIR/struct-fields-too-many.rs:18:9
    |
 18 |         bar: 0
-   |         ^^^^ `BuildData` does not have this field
+   |         ^^^ `BuildData` does not have this field
    |
    = note: available fields are: `foo`
 

Diff for: src/test/ui/suggest-private-fields.stderr

@@ -2,27 +2,27 @@ error[E0560]: struct `xc::B` has no field named `aa`
   --> $DIR/suggest-private-fields.rs:25:9
    |
 25 |         aa: 20,
-   |         ^^^ field does not exist - did you mean `a`?
+   |         ^^ field does not exist - did you mean `a`?
 
 error[E0560]: struct `xc::B` has no field named `bb`
   --> $DIR/suggest-private-fields.rs:27:9
    |
 27 |         bb: 20,
-   |         ^^^ `xc::B` does not have this field
+   |         ^^ `xc::B` does not have this field
    |
    = note: available fields are: `a`
 
 error[E0560]: struct `A` has no field named `aa`
   --> $DIR/suggest-private-fields.rs:32:9
    |
 32 |         aa: 20,
-   |         ^^^ field does not exist - did you mean `a`?
+   |         ^^ field does not exist - did you mean `a`?
 
 error[E0560]: struct `A` has no field named `bb`
   --> $DIR/suggest-private-fields.rs:34:9
    |
 34 |         bb: 20,
-   |         ^^^ field does not exist - did you mean `b`?
+   |         ^^ field does not exist - did you mean `b`?
 
 error: aborting due to 4 previous errors
 

Diff for: src/test/ui/union/union-fields-2.stderr

@@ -14,7 +14,7 @@ error[E0560]: union `U` has no field named `c`
   --> $DIR/union-fields-2.rs:20:29
    |
 20 |     let u = U { a: 0, b: 1, c: 2 }; //~ ERROR union expressions should have exactly one field
-   |                             ^^ `U` does not have this field
+   |                             ^ `U` does not have this field
    |
    = note: available fields are: `a`, `b`
 

Diff for: src/test/ui/union/union-suggest-field.stderr

@@ -2,7 +2,7 @@ error[E0560]: union `U` has no field named `principle`
   --> $DIR/union-suggest-field.rs:20:17
    |
 20 |     let u = U { principle: 0 };
-   |                 ^^^^^^^^^^ field does not exist - did you mean `principal`?
+   |                 ^^^^^^^^^ field does not exist - did you mean `principal`?
 
 error[E0609]: no field `principial` on type `U`
   --> $DIR/union-suggest-field.rs:22:15