syntax: Make is_path_start precise and improve some error messages about unexpected tokens

src/test/compile-fail/fail-simple.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-
-// error-pattern:unexpected token
 fn main() {
-  panic!(@);
+    panic!(@); //~ ERROR expected expression, found `@`
 }

src/test/compile-fail/issue-10636-2.rs

@@ -15,4 +15,4 @@ pub fn trace_option(option: Option<isize>) {
     option.map(|some| 42; //~ NOTE: unclosed delimiter
                           //~^ ERROR: expected one of
 } //~ ERROR: incorrect close delimiter
-//~^ ERROR: unexpected token
+//~^ ERROR: expected expression, found `)`

src/test/compile-fail/issue-31804.rs

@@ -13,4 +13,4 @@
 
 fn main() {
     let
-} //~ ERROR unexpected token: `}`
+} //~ ERROR expected pattern, found `}`

src/test/compile-fail/macro-context.rs

@@ -12,7 +12,7 @@
 
 // (typeof used because it's surprisingly hard to find an unparsed token after a stmt)
 macro_rules! m {
-    () => ( i ; typeof );   //~ ERROR `typeof` is a reserved keyword
+    () => ( i ; typeof );   //~ ERROR expected expression, found reserved keyword `typeof`
                             //~| ERROR macro expansion ignores token `typeof`
                             //~| ERROR macro expansion ignores token `;`
                             //~| ERROR macro expansion ignores token `;`

src/test/compile-fail/macro-incomplete-parse.rs

@@ -19,7 +19,7 @@ macro_rules! ignored_item {
 }
 
 macro_rules! ignored_expr {
-    () => ( 1,  //~ ERROR unexpected token: `,`
+    () => ( 1,  //~ ERROR expected expression, found `,`
             2 )
 }
 

src/test/compile-fail/reserved-become.rs

@@ -10,5 +10,5 @@
 
 fn main() {
     let become = 0;
-    //~^ ERROR `become` is a reserved keyword
+    //~^ ERROR expected pattern, found reserved keyword `become`
 }

src/test/compile-fail/token-error-correct.rs

@@ -13,8 +13,10 @@
 fn main() {
     foo(bar(; //~ NOTE: unclosed delimiter
     //~^ NOTE: unclosed delimiter
-    //~^^ ERROR: unexpected token: `;`
+    //~^^ ERROR: expected expression, found `;`
     //~^^^ ERROR: unresolved name `bar`
     //~^^^^ ERROR: unresolved name `foo`
+    //~^^^^^ ERROR: expected one of `)`, `,`, `.`, `<`, `?`
 } //~ ERROR: incorrect close delimiter: `}`
 //~^ ERROR: incorrect close delimiter: `}`
+//~^^ ERROR: expected expression, found `)`

src/test/compile-fail/vec-macro-with-comma-only.rs

@@ -9,5 +9,5 @@
 // except according to those terms.
 
 pub fn main() {
-    vec!(,); //~ ERROR unexpected token
+    vec!(,); //~ ERROR expected expression, found `,`
 }

src/test/parse-fail/issue-14303-path.rs

@@ -12,4 +12,4 @@
 
 fn bar<'a, T>(x: mymodule::X<'a, T, 'b, 'c>) {}
 //~^ ERROR lifetime parameters must be declared prior to type parameters
-//~^^ ERROR unexpected token
+//~^^ ERROR expected pattern, found `'c`

src/test/parse-fail/issue-32505.rs

@@ -11,7 +11,7 @@
 // compile-flags: -Z parse-only -Z continue-parse-after-error
 
 pub fn test() {
-    foo(|_|) //~ ERROR unexpected token: `)`
+    foo(|_|) //~ ERROR expected expression, found `)`
 }
 
 fn main() { }

src/test/parse-fail/keyword-abstract.rs

@@ -11,5 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn main() {
-    let abstract = (); //~ ERROR `abstract` is a reserved keyword
+    let abstract = (); //~ ERROR expected pattern, found reserved keyword `abstract`
 }

src/test/parse-fail/keyword-final.rs

@@ -11,5 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn main() {
-    let final = (); //~ ERROR `final` is a reserved keyword
+    let final = (); //~ ERROR expected pattern, found reserved keyword `final`
 }

src/test/parse-fail/keyword-override.rs

@@ -11,5 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn main() {
-    let override = (); //~ ERROR `override` is a reserved keyword
+    let override = (); //~ ERROR expected pattern, found reserved keyword `override`
 }

src/test/parse-fail/keyword-typeof.rs

@@ -11,5 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn main() {
-    let typeof = (); //~ ERROR `typeof` is a reserved keyword
+    let typeof = (); //~ ERROR expected pattern, found reserved keyword `typeof`
 }

src/test/parse-fail/keywords-followed-by-double-colon.rs

@@ -12,5 +12,5 @@
 
 fn main() {
     struct::foo();  //~ ERROR expected identifier
-    mut::baz(); //~ ERROR expected identifier
+    mut::baz(); //~ ERROR expected expression, found keyword `mut`
 }

src/test/parse-fail/match-arrows-block-then-binop.rs

@@ -14,6 +14,6 @@ fn main() {
 
     match 0 {
       0 => {
-      } + 5 //~ ERROR unexpected token: `+`
+      } + 5 //~ ERROR expected pattern, found `+`
     }
 }

src/test/parse-fail/obsolete-proc.rs

@@ -12,9 +12,8 @@
 
 // Test that we generate obsolete syntax errors around usages of `proc`.
 
-fn foo(p: proc()) { } //~ ERROR `proc` is a reserved keyword
+fn foo(p: proc()) { } //~ ERROR expected type, found reserved keyword `proc`
 
-fn bar() { proc() 1; } //~ ERROR `proc` is a reserved keyword
-                       //~^ ERROR expected
+fn bar() { proc() 1; } //~ ERROR expected expression, found reserved keyword `proc`
 
 fn main() { }

src/test/parse-fail/removed-syntax-mode.rs

@@ -10,4 +10,4 @@
 
 // compile-flags: -Z parse-only
 
-fn f(+x: isize) {} //~ ERROR unexpected token: `+`
+fn f(+x: isize) {} //~ ERROR expected pattern, found `+`

src/test/parse-fail/removed-syntax-mut-vec-expr.rs

@@ -11,7 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn f() {
-    let v = [mut 1, 2, 3, 4];
-    //~^  ERROR expected identifier, found keyword `mut`
-    //~^^ ERROR expected one of `!`, `,`, `.`, `::`, `;`, `?`, `]`, `{`, or an operator, found `1`
+    let v = [mut 1, 2, 3, 4]; //~ ERROR expected expression, found keyword `mut`
 }

src/test/parse-fail/removed-syntax-mut-vec-ty.rs

@@ -10,6 +10,4 @@
 
 // compile-flags: -Z parse-only
 
-type v = [mut isize];
-    //~^  ERROR expected identifier, found keyword `mut`
-    //~^^ ERROR expected one of `!`, `(`, `+`, `::`, `;`, `<`, or `]`, found `isize`
+type v = [mut isize]; //~ ERROR expected type, found keyword `mut`

src/test/parse-fail/removed-syntax-uniq-mut-expr.rs

@@ -11,7 +11,5 @@
 // compile-flags: -Z parse-only
 
 fn f() {
-    let a_box = box mut 42;
-    //~^  ERROR expected identifier, found keyword `mut`
-    //~^^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, or an operator, found `42`
+    let a_box = box mut 42; //~ ERROR expected expression, found keyword `mut`
 }

src/test/parse-fail/removed-syntax-uniq-mut-ty.rs

@@ -10,6 +10,4 @@
 
 // compile-flags: -Z parse-only
 
-type mut_box = Box<mut isize>;
-    //~^  ERROR expected identifier, found keyword `mut`
-    //~^^ ERROR expected one of `!`, `(`, `+`, `,`, `::`, `<`, or `>`, found `isize`
+type mut_box = Box<mut isize>; //~ ERROR expected type, found keyword `mut`

src/test/parse-fail/unsized2.rs

@@ -15,8 +15,5 @@
 fn f<X>() {}
 
 pub fn main() {
-    f<type>();
-    //~^ ERROR expected identifier, found keyword `type`
-    //~^^ ERROR: chained comparison
-    //~^^^ HELP: use `::<
+    f<type>(); //~ ERROR expected expression, found keyword `type`
 }