Tweak expand_incomplete_parse warning.

By using `token_descr`, as is done for many other errors, we can get
slightly better descriptions in error messages, e.g.
"macro expansion ignores token `let` and any following" becomes
"macro expansion ignores keyword `let` and any tokens following".

This will be more important once invisible delimiters start being
mentioned in error messages -- without this commit, that leads to error
messages such as "error at ``" because invisible delimiters are
pretty printed as an empty string.

compiler/rustc_expand/messages.ftl

@@ -74,7 +74,7 @@ expand_helper_attribute_name_invalid =
     `{$name}` cannot be a name of derive helper attribute
 
 expand_incomplete_parse =
-    macro expansion ignores token `{$token}` and any following
+    macro expansion ignores {$descr} and any tokens following
     .label = caused by the macro expansion here
     .note = the usage of `{$macro_path}!` is likely invalid in {$kind_name} context
     .suggestion_add_semi = you might be missing a semicolon here

compiler/rustc_expand/src/errors.rs

@@ -275,7 +275,7 @@ pub(crate) struct UnsupportedKeyValue {
 pub(crate) struct IncompleteParse<'a> {
     #[primary_span]
     pub span: Span,
-    pub token: Cow<'a, str>,
+    pub descr: String,
     #[label]
     pub label_span: Span,
     pub macro_path: &'a ast::Path,

compiler/rustc_expand/src/expand.rs

@@ -21,6 +21,7 @@
 use rustc_feature::Features;
 use rustc_parse::parser::{
     AttemptLocalParseRecovery, CommaRecoveryMode, ForceCollect, Parser, RecoverColon, RecoverComma,
+    token_descr,
 };
 use rustc_parse::validate_attr;
 use rustc_session::lint::BuiltinLintDiag;
@@ -1013,7 +1014,7 @@ pub(crate) fn ensure_complete_parse<'a>(
     span: Span,
 ) {
     if parser.token != token::Eof {
-        let token = pprust::token_to_string(&parser.token);
+        let descr = token_descr(&parser.token);
         // Avoid emitting backtrace info twice.
         let def_site_span = parser.token.span.with_ctxt(SyntaxContext::root());
 
@@ -1029,7 +1030,7 @@ pub(crate) fn ensure_complete_parse<'a>(
 
         parser.dcx().emit_err(IncompleteParse {
             span: def_site_span,
-            token,
+            descr,
             label_span: span,
             macro_path,
             kind_name,

compiler/rustc_parse/src/parser/mod.rs

@@ -424,7 +424,7 @@ pub(super) fn from_token(token: &Token) -> Option<Self> {
     }
 }
 
-pub(super) fn token_descr(token: &Token) -> String {
+pub fn token_descr(token: &Token) -> String {
     let name = pprust::token_to_string(token).to_string();
 
     let kind = match (TokenDescription::from_token(token), &token.kind) {

tests/ui/macros/issue-118786.rs

@@ -5,7 +5,7 @@
 macro_rules! make_macro {
     ($macro_name:tt) => {
         macro_rules! $macro_name {
-        //~^ ERROR macro expansion ignores token `{` and any following
+        //~^ ERROR macro expansion ignores `{` and any tokens following
         //~| ERROR cannot find macro `macro_rules` in this scope
         //~| put a macro name here
             () => {}

tests/ui/macros/issue-118786.stderr

@@ -13,7 +13,7 @@ help: add a semicolon
 LL |         macro_rules! $macro_name; {
    |                                 +
 
-error: macro expansion ignores token `{` and any following
+error: macro expansion ignores `{` and any tokens following
   --> $DIR/issue-118786.rs:7:34
    |
 LL |         macro_rules! $macro_name {

tests/ui/macros/issue-30007.rs

@@ -1,5 +1,5 @@
 macro_rules! t {
-    () => ( String ; );     //~ ERROR macro expansion ignores token `;`
+    () => ( String ; );     //~ ERROR macro expansion ignores `;`
 }
 
 fn main() {

tests/ui/macros/issue-30007.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `;` and any following
+error: macro expansion ignores `;` and any tokens following
   --> $DIR/issue-30007.rs:2:20
    |
 LL |     () => ( String ; );

tests/ui/macros/issue-54441.rs

@@ -1,6 +1,6 @@
 macro_rules! m {
     () => {
-        let //~ ERROR macro expansion ignores token `let` and any following
+        let //~ ERROR macro expansion ignores keyword `let` and any tokens following
     };
 }
 

tests/ui/macros/issue-54441.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `let` and any following
+error: macro expansion ignores keyword `let` and any tokens following
   --> $DIR/issue-54441.rs:3:9
    |
 LL |         let

tests/ui/macros/macro-context.rs

@@ -1,9 +1,9 @@
 // (typeof used because it's surprisingly hard to find an unparsed token after a stmt)
 macro_rules! m {
     () => ( i ; typeof );   //~ ERROR expected expression, found reserved keyword `typeof`
-                            //~| ERROR macro expansion ignores token `typeof`
+                            //~| ERROR macro expansion ignores reserved keyword `typeof`
-                            //~| ERROR macro expansion ignores token `;`
+                            //~| ERROR macro expansion ignores `;`
-                            //~| ERROR macro expansion ignores token `;`
+                            //~| ERROR macro expansion ignores `;`
                             //~| ERROR cannot find type `i` in this scope
                             //~| ERROR cannot find value `i` in this scope
                             //~| WARN trailing semicolon in macro

tests/ui/macros/macro-context.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `;` and any following
+error: macro expansion ignores `;` and any tokens following
   --> $DIR/macro-context.rs:3:15
    |
 LL |     () => ( i ; typeof );
@@ -9,7 +9,7 @@ LL |     let a: m!();
    |
    = note: the usage of `m!` is likely invalid in type context
 
-error: macro expansion ignores token `typeof` and any following
+error: macro expansion ignores reserved keyword `typeof` and any tokens following
   --> $DIR/macro-context.rs:3:17
    |
 LL |     () => ( i ; typeof );
@@ -20,7 +20,7 @@ LL |     let i = m!();
    |
    = note: the usage of `m!` is likely invalid in expression context
 
-error: macro expansion ignores token `;` and any following
+error: macro expansion ignores `;` and any tokens following
   --> $DIR/macro-context.rs:3:15
    |
 LL |     () => ( i ; typeof );

tests/ui/macros/macro-in-expression-context.fixed

@@ -11,7 +11,7 @@ macro_rules! foo {
         //~| NOTE `#[warn(semicolon_in_expressions_from_macros)]` on by default
         assert_eq!("B", "B");
     }
-    //~^^ ERROR macro expansion ignores token `assert_eq` and any following
+    //~^^ ERROR macro expansion ignores `assert_eq` and any tokens following
     //~| NOTE the usage of `foo!` is likely invalid in expression context
 }
 

tests/ui/macros/macro-in-expression-context.rs

@@ -11,7 +11,7 @@ macro_rules! foo {
         //~| NOTE `#[warn(semicolon_in_expressions_from_macros)]` on by default
         assert_eq!("B", "B");
     }
-    //~^^ ERROR macro expansion ignores token `assert_eq` and any following
+    //~^^ ERROR macro expansion ignores `assert_eq` and any tokens following
     //~| NOTE the usage of `foo!` is likely invalid in expression context
 }
 

tests/ui/macros/macro-in-expression-context.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `assert_eq` and any following
+error: macro expansion ignores `assert_eq` and any tokens following
   --> $DIR/macro-in-expression-context.rs:12:9
    |
 LL |         assert_eq!("B", "B");

tests/ui/macros/syntax-error-recovery.rs

@@ -10,7 +10,7 @@ pub enum TokenKind {
     };
 }
 //~^^^^^ ERROR expected one of `(`, `,`, `=`, `{`, or `}`, found type `(String)`
-//~| ERROR macro expansion ignores token `(String)` and any following
+//~| ERROR macro expansion ignores type `(String)` and any tokens following
 
 values!(STRING(1) as (String) => cfg(test),);
 //~^ ERROR expected one of `!` or `::`, found `<eof>`

tests/ui/macros/syntax-error-recovery.stderr

@@ -10,7 +10,7 @@ LL | values!(STRING(1) as (String) => cfg(test),);
    = help: enum variants can be `Variant`, `Variant = <integer>`, `Variant(Type, ..., TypeN)` or `Variant { fields: Types }`
    = note: this error originates in the macro `values` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: macro expansion ignores token `(String)` and any following
+error: macro expansion ignores type `(String)` and any tokens following
   --> $DIR/syntax-error-recovery.rs:7:26
    |
 LL |                 $token $($inner)? = $value,

tests/ui/parser/macro/macro-expand-to-match-arm.rs

@@ -1,7 +1,7 @@
 macro_rules! arm {
     ($pattern:pat => $block:block) => {
         $pattern => $block
-        //~^ ERROR macro expansion ignores token `=>` and any following
+        //~^ ERROR macro expansion ignores `=>` and any tokens following
         //~| NOTE the usage of `arm!` is likely invalid in pattern context
         //~| NOTE macros cannot expand to match arms
     };

tests/ui/parser/macro/macro-expand-to-match-arm.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `=>` and any following
+error: macro expansion ignores `=>` and any tokens following
   --> $DIR/macro-expand-to-match-arm.rs:3:18
    |
 LL |         $pattern => $block

tests/ui/parser/macro/macro-incomplete-parse.rs

@@ -2,7 +2,7 @@ macro_rules! ignored_item {
     () => {
         fn foo() {}
         fn bar() {}
-        , //~ ERROR macro expansion ignores token `,`
+        , //~ ERROR macro expansion ignores `,`
     }
 }
 
@@ -13,7 +13,7 @@ macro_rules! ignored_expr {
 }
 
 macro_rules! ignored_pat {
-    () => ( 1, 2 ) //~ ERROR macro expansion ignores token `,`
+    () => ( 1, 2 ) //~ ERROR macro expansion ignores `,`
 }
 
 ignored_item!();

tests/ui/parser/macro/macro-incomplete-parse.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `,` and any following
+error: macro expansion ignores `,` and any tokens following
   --> $DIR/macro-incomplete-parse.rs:5:9
    |
 LL |         ,
@@ -20,7 +20,7 @@ LL |     ignored_expr!();
    |
    = note: this error originates in the macro `ignored_expr` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: macro expansion ignores token `,` and any following
+error: macro expansion ignores `,` and any tokens following
   --> $DIR/macro-incomplete-parse.rs:16:14
    |
 LL |     () => ( 1, 2 )

tests/ui/parser/macro/trait-non-item-macros.rs

@@ -1,7 +1,7 @@
 macro_rules! bah {
     ($a:expr) => {
         $a
-    }; //~^ ERROR macro expansion ignores token `2` and any following
+    }; //~^ ERROR macro expansion ignores expression `2` and any tokens following
 }
 
 trait Bar {

tests/ui/parser/macro/trait-non-item-macros.stderr

@@ -1,4 +1,4 @@
-error: macro expansion ignores token `2` and any following
+error: macro expansion ignores expression `2` and any tokens following
   --> $DIR/trait-non-item-macros.rs:3:9
    |
 LL |         $a

tests/ui/proc-macro/attr-invalid-exprs.rs

@@ -13,7 +13,7 @@ fn main() {
     //~^ ERROR expected expression, found end of macro arguments
 
     let _ = #[duplicate] "Hello, world!";
-    //~^ ERROR macro expansion ignores token `,` and any following
+    //~^ ERROR macro expansion ignores `,` and any tokens following
 
     let _ = {
         #[no_output]
@@ -22,7 +22,7 @@ fn main() {
 
     let _ = {
         #[duplicate]
-        //~^ ERROR macro expansion ignores token `,` and any following
+        //~^ ERROR macro expansion ignores `,` and any tokens following
         "Hello, world!"
     };
 }

tests/ui/proc-macro/attr-invalid-exprs.stderr

@@ -4,7 +4,7 @@ error: expected expression, found end of macro arguments
 LL |     let _ = #[no_output] "Hello, world!";
    |             ^^^^^^^^^^^^
 
-error: macro expansion ignores token `,` and any following
+error: macro expansion ignores `,` and any tokens following
   --> $DIR/attr-invalid-exprs.rs:15:13
    |
 LL |     let _ = #[duplicate] "Hello, world!";
@@ -16,7 +16,7 @@ help: you might be missing a semicolon here
 LL |     let _ = #[duplicate]; "Hello, world!";
    |                         +
 
-error: macro expansion ignores token `,` and any following
+error: macro expansion ignores `,` and any tokens following
   --> $DIR/attr-invalid-exprs.rs:24:9
    |
 LL |         #[duplicate]

tests/ui/proc-macro/expand-expr.rs

@@ -114,8 +114,8 @@ macro_rules! mac {
 
 // We get errors reported and recover during macro expansion if the macro
 // doesn't produce a valid expression.
-expand_expr_is!("string", echo_tts!("string"; hello)); //~ ERROR: macro expansion ignores token `hello` and any following
+expand_expr_is!("string", echo_tts!("string"; hello)); //~ ERROR: macro expansion ignores `hello` and any tokens following
-expand_expr_is!("string", echo_pm!("string"; hello)); //~ ERROR: macro expansion ignores token `;` and any following
+expand_expr_is!("string", echo_pm!("string"; hello)); //~ ERROR: macro expansion ignores `;` and any tokens following
 
 // For now, fail if a non-literal expression is expanded.
 expand_expr_fail!(arbitrary_expression() + "etc");

tests/ui/proc-macro/expand-expr.stderr

@@ -22,7 +22,7 @@ error: expected expression, found `$`
 LL | expand_expr_fail!(echo_pm!($));
    |                            ^ expected expression
 
-error: macro expansion ignores token `hello` and any following
+error: macro expansion ignores `hello` and any tokens following
   --> $DIR/expand-expr.rs:117:47
    |
 LL | expand_expr_is!("string", echo_tts!("string"; hello));
@@ -34,7 +34,7 @@ help: you might be missing a semicolon here
 LL | expand_expr_is!("string", echo_tts!("string"; hello););
    |                                                     +
 
-error: macro expansion ignores token `;` and any following
+error: macro expansion ignores `;` and any tokens following
   --> $DIR/expand-expr.rs:118:44
    |
 LL | expand_expr_is!("string", echo_pm!("string"; hello));