Rollup merge of rust-lang#54181 - vi:hint_and_or, r=estebank

Suggest && and || instead of 'and' and 'or'

Resolves rust-lang#54109.

Note: competing pull reqeust: rust-lang#54179

r? @csmoe

src/libsyntax/parse/parser.rs

@@ -732,6 +732,22 @@ impl<'a> Parser<'a> {
                   format!("expected {} here", expect)))
             };
             let mut err = self.fatal(&msg_exp);
+            if self.token.is_ident_named("and") {
+                err.span_suggestion_short_with_applicability(
+                    self.span,
+                    "use `&&` instead of `and` for the boolean operator",
+                    "&&".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            if self.token.is_ident_named("or") {
+                err.span_suggestion_short_with_applicability(
+                    self.span,
+                    "use `||` instead of `or` for the boolean operator",
+                    "||".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
             let sp = if self.token == token::Token::Eof {
                 // This is EOF, don't want to point at the following char, but rather the last token
                 self.prev_span
@@ -4751,6 +4767,23 @@ impl<'a> Parser<'a> {
                 e.span_label(sp, "expected `{`");
             }
 
+            if self.token.is_ident_named("and") {
+                e.span_suggestion_short_with_applicability(
+                    self.span,
+                    "use `&&` instead of `and` for the boolean operator",
+                    "&&".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            if self.token.is_ident_named("or") {
+                e.span_suggestion_short_with_applicability(
+                    self.span,
+                    "use `||` instead of `or` for the boolean operator",
+                    "||".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+
             // Check to see if the user has written something like
             //
             //    if (cond)

src/test/ui/did_you_mean/issue-54109-and_instead_of_ampersands.rs

@@ -0,0 +1,66 @@
+// 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.
+
+fn test_and() {
+    let a = true;
+    let b = false;
+    if a and b {
+        //~^ ERROR expected `{`, found `and`
+        println!("both");
+    }
+}
+
+fn test_or() {
+    let a = true;
+    let b = false;
+    if a or b {
+        //~^ ERROR expected `{`, found `or`
+        println!("both");
+    }
+}
+
+fn test_and_par() {
+    let a = true;
+    let b = false;
+    if (a and b) {
+        //~^ ERROR expected one of `!`, `)`, `,`, `.`, `::`, `?`, `{`, or an operator, found `and`
+        println!("both");
+    }
+}
+
+fn test_or_par() {
+    let a = true;
+    let b = false;
+    if (a or b) {
+        //~^ ERROR expected one of `!`, `)`, `,`, `.`, `::`, `?`, `{`, or an operator, found `or`
+        println!("both");
+    }
+}
+
+fn test_while_and() {
+    let a = true;
+    let b = false;
+    while a and b {
+        //~^ ERROR expected one of `!`, `.`, `::`, `?`, `{`, or an operator, found `and`
+        println!("both");
+    }
+}
+
+fn test_while_or() {
+    let a = true;
+    let b = false;
+    while a or b {
+        //~^ ERROR expected one of `!`, `.`, `::`, `?`, `{`, or an operator, found `or`
+        println!("both");
+    }
+}
+
+fn main() {
+}

src/test/ui/did_you_mean/issue-54109-and_instead_of_ampersands.stderr

@@ -0,0 +1,54 @@
+error: expected `{`, found `and`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:14:10
+   |
+LL |     if a and b {
+   |     --   ^^^ help: use `&&` instead of `and` for the boolean operator
+   |     |
+   |     this `if` statement has a condition, but no block
+
+error: expected `{`, found `or`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:23:10
+   |
+LL |     if a or b {
+   |     --   ^^ help: use `||` instead of `or` for the boolean operator
+   |     |
+   |     this `if` statement has a condition, but no block
+
+error: expected one of `!`, `)`, `,`, `.`, `::`, `?`, `{`, or an operator, found `and`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:32:11
+   |
+LL |     if (a and b) {
+   |           ^^^
+   |           |
+   |           expected one of 8 possible tokens here
+   |           help: use `&&` instead of `and` for the boolean operator
+
+error: expected one of `!`, `)`, `,`, `.`, `::`, `?`, `{`, or an operator, found `or`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:41:11
+   |
+LL |     if (a or b) {
+   |           ^^
+   |           |
+   |           expected one of 8 possible tokens here
+   |           help: use `||` instead of `or` for the boolean operator
+
+error: expected one of `!`, `.`, `::`, `?`, `{`, or an operator, found `and`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:50:13
+   |
+LL |     while a and b {
+   |             ^^^
+   |             |
+   |             expected one of `!`, `.`, `::`, `?`, `{`, or an operator here
+   |             help: use `&&` instead of `and` for the boolean operator
+
+error: expected one of `!`, `.`, `::`, `?`, `{`, or an operator, found `or`
+  --> $DIR/issue-54109-and_instead_of_ampersands.rs:59:13
+   |
+LL |     while a or b {
+   |             ^^
+   |             |
+   |             expected one of `!`, `.`, `::`, `?`, `{`, or an operator here
+   |             help: use `||` instead of `or` for the boolean operator
+
+error: aborting due to 6 previous errors
+