Remove spurious complaint about missing expression for bare semicolons

Author: estebank

src/libsyntax/parse/parser.rs

@@ -731,7 +731,7 @@ impl<'a> Parser<'a> {
                     Applicability::MaybeIncorrect,
                 );
                 err.emit();
-                // self.expected_tokens.clear();  // reduce errors
+                self.expected_tokens.clear();  // reduce errors
                 Ok(true)
             }
             _ => Err(err),
@@ -2814,6 +2814,21 @@ impl<'a> Parser<'a> {
                     hi = pth.span;
                     ex = ExprKind::Path(None, pth);
                 } else {
+                    if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
+                        // Don't complain about bare semicolons after unclosed braces
+                        // recovery in order to keep the error count down. Fixing the
+                        // delimiters will possibly also fix the bare semicolon found in
+                        // expression context. For example, silence the following error:
+                        // ```
+                        // error: expected expression, found `;`
+                        //  --> file.rs:2:13
+                        //   |
+                        // 2 |     foo(bar(;
+                        //   |             ^ expected expression
+                        // ```
+                        self.bump();
+                        return Ok(self.mk_expr(self.span, ExprKind::Err, ThinVec::new()));
+                    }
                     match self.parse_literal_maybe_minus() {
                         Ok(expr) => {
                             hi = expr.span;

src/test/ui/resolve/token-error-correct.rs

@@ -2,6 +2,8 @@
 
 fn main() {
     foo(bar(;
-    //~^ ERROR: expected expression, found `;`
+    //~^ ERROR cannot find function `bar` in this scope
 }
 //~^ ERROR: incorrect close delimiter: `}`
+
+fn foo(_: usize) {}

src/test/ui/resolve/token-error-correct.stderr

@@ -1,19 +1,20 @@
-error: expected expression, found `;`
-  --> $DIR/token-error-correct.rs:4:13
-   |
-LL |     foo(bar(;
-   |             ^ expected expression
-
 error: incorrect close delimiter: `}`
   --> $DIR/token-error-correct.rs:6:1
    |
 LL | fn main() {
    |           - close delimiter possibly meant for this
 LL |     foo(bar(;
    |            - un-closed delimiter
-LL |     //~^ ERROR: expected expression, found `;`
+LL |     //~^ ERROR cannot find function `bar` in this scope
 LL | }
    | ^ incorrect close delimiter
 
+error[E0425]: cannot find function `bar` in this scope
+  --> $DIR/token-error-correct.rs:4:9
+   |
+LL |     foo(bar(;
+   |         ^^^ not found in this scope
+
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0425`.