mbe: Extend metavariable expression tests

Add tests showing the current state to make it more clear when output
gets updated later in refactoring.

6 files changed, 247 insertions, 62 deletions

diff --git a/tests/ui/macros/metavar-expressions/concat-trace-errors.rs b/tests/ui/macros/metavar-expressions/concat-trace-errors.rs
new file mode 100644
index 00000000000..45407f5e86d
--- /dev/null
+++ b/tests/ui/macros/metavar-expressions/concat-trace-errors.rs
@@ -0,0 +1,33 @@
+// Our diagnostics should be able to point to a specific input that caused an invalid
+// identifier.
+
+#![feature(macro_metavar_expr_concat)]
+
+// See what we can do without expanding anything
+macro_rules! pre_expansion {
+    ($a:ident) => {
+        ${concat("hi", " bye ")};
+        ${concat("hi", "-", "bye")};
+        ${concat($a, "-")};
+    }
+}
+
+macro_rules! post_expansion {
+    ($a:literal) => {
+        const _: () = ${concat("hi", $a, "bye")};
+        //~^ ERROR is not generating a valid identifier
+    }
+}
+
+post_expansion!("!");
+
+macro_rules! post_expansion_many {
+    ($a:ident, $b:ident, $c:ident, $d:literal, $e:ident) => {
+        const _: () = ${concat($a, $b, $c, $d, $e)};
+        //~^ ERROR is not generating a valid identifier
+    }
+}
+
+post_expansion_many!(a, b, c, ".d", e);
+
+fn main() {}
diff --git a/tests/ui/macros/metavar-expressions/concat-trace-errors.stderr b/tests/ui/macros/metavar-expressions/concat-trace-errors.stderr
new file mode 100644
index 00000000000..dac8b58a15c
--- /dev/null
+++ b/tests/ui/macros/metavar-expressions/concat-trace-errors.stderr
@@ -0,0 +1,24 @@
+error: `${concat(..)}` is not generating a valid identifier
+  --> $DIR/concat-trace-errors.rs:17:24
+   |
+LL |         const _: () = ${concat("hi", $a, "bye")};
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | post_expansion!("!");
+   | -------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `post_expansion` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: `${concat(..)}` is not generating a valid identifier
+  --> $DIR/concat-trace-errors.rs:26:24
+   |
+LL |         const _: () = ${concat($a, $b, $c, $d, $e)};
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | post_expansion_many!(a, b, c, ".d", e);
+   | -------------------------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `post_expansion_many` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/macros/metavar-expressions/concat-usage-errors.rs b/tests/ui/macros/metavar-expressions/concat-usage-errors.rs
index f86a2328da2..7d8756de9e2 100644
--- a/tests/ui/macros/metavar-expressions/concat-usage-errors.rs
+++ b/tests/ui/macros/metavar-expressions/concat-usage-errors.rs
@@ -1,3 +1,5 @@
+//@ edition: 2021
+
 #![feature(macro_metavar_expr_concat)]
 
 macro_rules! syntax_errors {
@@ -90,11 +92,31 @@ macro_rules! unsupported_literals {
         //~| ERROR expected pattern
         let ${concat(_a, 1)}: () = ();
         //~^ ERROR expected identifier or string literal
+        let ${concat(_a, 1.5)}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat(_a, c"hi")}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat(_a, b"hi")}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat(_a, b'b')}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat(_a, b'b')}: () = ();
+        //~^ ERROR expected identifier or string literal
 
         let ${concat($ident, 'b')}: () = ();
         //~^ ERROR expected identifier or string literal
         let ${concat($ident, 1)}: () = ();
         //~^ ERROR expected identifier or string literal
+        let ${concat($ident, 1.5)}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat($ident, c"hi")}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat($ident, b"hi")}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat($ident, b'b')}: () = ();
+        //~^ ERROR expected identifier or string literal
+        let ${concat($ident, b'b')}: () = ();
+        //~^ ERROR expected identifier or string literal
     }};
 }
 
diff --git a/tests/ui/macros/metavar-expressions/concat-usage-errors.stderr b/tests/ui/macros/metavar-expressions/concat-usage-errors.stderr
index 629843ecbda..8be3e792ec3 100644
--- a/tests/ui/macros/metavar-expressions/concat-usage-errors.stderr
+++ b/tests/ui/macros/metavar-expressions/concat-usage-errors.stderr
@@ -1,71 +1,131 @@
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:5:10
+  --> $DIR/concat-usage-errors.rs:7:10
    |
 LL |         ${concat()}
    |          ^^^^^^^^^^
 
 error: `concat` must have at least two elements
-  --> $DIR/concat-usage-errors.rs:8:11
+  --> $DIR/concat-usage-errors.rs:10:11
    |
 LL |         ${concat(aaaa)}
    |           ^^^^^^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:11:10
+  --> $DIR/concat-usage-errors.rs:13:10
    |
 LL |         ${concat(aaaa,)}
    |          ^^^^^^^^^^^^^^^
 
 error: expected comma
-  --> $DIR/concat-usage-errors.rs:16:10
+  --> $DIR/concat-usage-errors.rs:18:10
    |
 LL |         ${concat(aaaa aaaa)}
    |          ^^^^^^^^^^^^^^^^^^^
 
 error: `concat` must have at least two elements
-  --> $DIR/concat-usage-errors.rs:19:11
+  --> $DIR/concat-usage-errors.rs:21:11
    |
 LL |         ${concat($ex)}
    |           ^^^^^^
 
 error: expected comma
-  --> $DIR/concat-usage-errors.rs:25:10
+  --> $DIR/concat-usage-errors.rs:27:10
    |
 LL |         ${concat($ex, aaaa 123)}
    |          ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:28:10
+  --> $DIR/concat-usage-errors.rs:30:10
    |
 LL |         ${concat($ex, aaaa,)}
    |          ^^^^^^^^^^^^^^^^^^^^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:88:26
+  --> $DIR/concat-usage-errors.rs:90:26
    |
 LL |         let ${concat(_a, 'b')}: () = ();
    |                          ^^^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:91:26
+  --> $DIR/concat-usage-errors.rs:93:26
    |
 LL |         let ${concat(_a, 1)}: () = ();
    |                          ^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:94:30
+  --> $DIR/concat-usage-errors.rs:95:26
+   |
+LL |         let ${concat(_a, 1.5)}: () = ();
+   |                          ^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:97:26
+   |
+LL |         let ${concat(_a, c"hi")}: () = ();
+   |                          ^^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:99:26
+   |
+LL |         let ${concat(_a, b"hi")}: () = ();
+   |                          ^^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:101:26
+   |
+LL |         let ${concat(_a, b'b')}: () = ();
+   |                          ^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:103:26
+   |
+LL |         let ${concat(_a, b'b')}: () = ();
+   |                          ^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:106:30
    |
 LL |         let ${concat($ident, 'b')}: () = ();
    |                              ^^^
 
 error: expected identifier or string literal
-  --> $DIR/concat-usage-errors.rs:96:30
+  --> $DIR/concat-usage-errors.rs:108:30
    |
 LL |         let ${concat($ident, 1)}: () = ();
    |                              ^
 
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:110:30
+   |
+LL |         let ${concat($ident, 1.5)}: () = ();
+   |                              ^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:112:30
+   |
+LL |         let ${concat($ident, c"hi")}: () = ();
+   |                              ^^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:114:30
+   |
+LL |         let ${concat($ident, b"hi")}: () = ();
+   |                              ^^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:116:30
+   |
+LL |         let ${concat($ident, b'b')}: () = ();
+   |                              ^^^^
+
+error: expected identifier or string literal
+  --> $DIR/concat-usage-errors.rs:118:30
+   |
+LL |         let ${concat($ident, b'b')}: () = ();
+   |                              ^^^^
+
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:22:19
+  --> $DIR/concat-usage-errors.rs:24:19
    |
 LL |         ${concat($ex, aaaa)}
    |                   ^^
@@ -73,13 +133,13 @@ LL |         ${concat($ex, aaaa)}
    = note: currently only string literals are supported
 
 error: variable `foo` is not recognized in meta-variable expression
-  --> $DIR/concat-usage-errors.rs:35:30
+  --> $DIR/concat-usage-errors.rs:37:30
    |
 LL |         const ${concat(FOO, $foo)}: i32 = 2;
    |                              ^^^
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:42:14
+  --> $DIR/concat-usage-errors.rs:44:14
    |
 LL |         let ${concat("1", $ident)}: () = ();
    |              ^^^^^^^^^^^^^^^^^^^^^
@@ -90,7 +150,7 @@ LL |     starting_number!(_abc);
    = note: this error originates in the macro `starting_number` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:55:14
+  --> $DIR/concat-usage-errors.rs:57:14
    |
 LL |         let ${concat("\u{00BD}", $ident)}: () = ();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -101,7 +161,7 @@ LL |     starting_invalid_unicode!(_abc);
    = note: this error originates in the macro `starting_invalid_unicode` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:74:14
+  --> $DIR/concat-usage-errors.rs:76:14
    |
 LL |         let ${concat($ident, "\u{00BD}")}: () = ();
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -112,7 +172,7 @@ LL |     ending_invalid_unicode!(_abc);
    = note: this error originates in the macro `ending_invalid_unicode` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected pattern, found `$`
-  --> $DIR/concat-usage-errors.rs:88:13
+  --> $DIR/concat-usage-errors.rs:90:13
    |
 LL |         let ${concat(_a, 'b')}: () = ();
    |             ^ expected pattern
@@ -123,7 +183,7 @@ LL |     unsupported_literals!(_abc);
    = note: this error originates in the macro `unsupported_literals` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:81:14
+  --> $DIR/concat-usage-errors.rs:83:14
    |
 LL |         let ${concat("", "")}: () = ();
    |              ^^^^^^^^^^^^^^^^
@@ -134,7 +194,7 @@ LL |     empty!();
    = note: this error originates in the macro `empty` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -145,7 +205,7 @@ LL |     bad_literal_string!("\u{00BD}");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -156,7 +216,7 @@ LL |     bad_literal_string!("\x41");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -167,7 +227,7 @@ LL |     bad_literal_string!("🤷");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -178,7 +238,7 @@ LL |     bad_literal_string!("d[-_-]b");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -189,7 +249,7 @@ LL |     bad_literal_string!("-1");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -200,7 +260,7 @@ LL |     bad_literal_string!("1.0");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `${concat(..)}` is not generating a valid identifier
-  --> $DIR/concat-usage-errors.rs:103:16
+  --> $DIR/concat-usage-errors.rs:125:16
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -211,7 +271,7 @@ LL |     bad_literal_string!("'1'");
    = note: this error originates in the macro `bad_literal_string` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:116:31
+  --> $DIR/concat-usage-errors.rs:138:31
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                               ^^^^^^^
@@ -219,7 +279,7 @@ LL |         const ${concat(_foo, $literal)}: () = ();
    = note: currently only string literals are supported
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:116:31
+  --> $DIR/concat-usage-errors.rs:138:31
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                               ^^^^^^^
@@ -228,7 +288,7 @@ LL |         const ${concat(_foo, $literal)}: () = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:116:31
+  --> $DIR/concat-usage-errors.rs:138:31
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                               ^^^^^^^
@@ -237,7 +297,7 @@ LL |         const ${concat(_foo, $literal)}: () = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:116:31
+  --> $DIR/concat-usage-errors.rs:138:31
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                               ^^^^^^^
@@ -246,7 +306,7 @@ LL |         const ${concat(_foo, $literal)}: () = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:116:31
+  --> $DIR/concat-usage-errors.rs:138:31
    |
 LL |         const ${concat(_foo, $literal)}: () = ();
    |                               ^^^^^^^
@@ -255,7 +315,7 @@ LL |         const ${concat(_foo, $literal)}: () = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:127:31
+  --> $DIR/concat-usage-errors.rs:149:31
    |
 LL |         const ${concat(_foo, $tt)}: () = ();
    |                               ^^
@@ -263,7 +323,7 @@ LL |         const ${concat(_foo, $tt)}: () = ();
    = note: currently only string literals are supported
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:127:31
+  --> $DIR/concat-usage-errors.rs:149:31
    |
 LL |         const ${concat(_foo, $tt)}: () = ();
    |                               ^^
@@ -272,7 +332,7 @@ LL |         const ${concat(_foo, $tt)}: () = ();
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`
-  --> $DIR/concat-usage-errors.rs:127:31
+  --> $DIR/concat-usage-errors.rs:149:31
    |
 LL |         const ${concat(_foo, $tt)}: () = ();
    |                               ^^
@@ -280,5 +340,5 @@ LL |         const ${concat(_foo, $tt)}: () = ();
    = note: currently only string literals are supported
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error: aborting due to 33 previous errors
+error: aborting due to 43 previous errors
 
diff --git a/tests/ui/macros/metavar-expressions/syntax-errors.rs b/tests/ui/macros/metavar-expressions/syntax-errors.rs
index 8735da352d8..8fc76a74baa 100644
--- a/tests/ui/macros/metavar-expressions/syntax-errors.rs
+++ b/tests/ui/macros/metavar-expressions/syntax-errors.rs
@@ -28,13 +28,35 @@ macro_rules! metavar_with_literal_suffix {
     //~^ ERROR only unsuffixes integer literals are supported in meta-variable expressions
 }
 
-macro_rules! metavar_without_parens {
+macro_rules! mve_without_parens {
+    ( $( $i:ident ),* ) => { ${ count } };
+    //~^ ERROR meta-variable expression parameter must be wrapped in parentheses
+}
+
+#[rustfmt::skip]
+macro_rules! empty_expression {
+    () => { ${} };
+    //~^ ERROR expected identifier or string literal
+}
+
+#[rustfmt::skip]
+macro_rules! open_brackets_with_lit {
+     () => { ${ "hi" } };
+     //~^ ERROR expected identifier
+ }
+
+macro_rules! mve_wrong_delim {
     ( $( $i:ident ),* ) => { ${ count{i} } };
     //~^ ERROR meta-variable expression parameter must be wrapped in parentheses
 }
 
+macro_rules! invalid_metavar {
+    () => { ${ignore($123)} }
+    //~^ ERROR expected identifier, found `123`
+}
+
 #[rustfmt::skip]
-macro_rules! open_brackets_without_tokens {
+macro_rules! open_brackets_with_group {
     ( $( $i:ident ),* ) => { ${ {} } };
     //~^ ERROR expected identifier
 }
diff --git a/tests/ui/macros/metavar-expressions/syntax-errors.stderr b/tests/ui/macros/metavar-expressions/syntax-errors.stderr
index 291e27924c8..20d2358facc 100644
--- a/tests/ui/macros/metavar-expressions/syntax-errors.stderr
+++ b/tests/ui/macros/metavar-expressions/syntax-errors.stderr
@@ -43,158 +43,182 @@ LL |     ( $( $i:ident ),* ) => { ${ index(1u32) } };
 error: meta-variable expression parameter must be wrapped in parentheses
   --> $DIR/syntax-errors.rs:32:33
    |
+LL |     ( $( $i:ident ),* ) => { ${ count } };
+   |                                 ^^^^^
+
+error: meta-variable expression parameter must be wrapped in parentheses
+  --> $DIR/syntax-errors.rs:49:33
+   |
 LL |     ( $( $i:ident ),* ) => { ${ count{i} } };
    |                                 ^^^^^
 
+error: expected identifier, found `123`
+  --> $DIR/syntax-errors.rs:54:23
+   |
+LL |     () => { ${ignore($123)} }
+   |                       ^^^ help: try removing `123`
+
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:44:19
+  --> $DIR/syntax-errors.rs:66:19
    |
 LL |         ${count() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:44:19
+  --> $DIR/syntax-errors.rs:66:19
    |
 LL |         ${count() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:46:20
+  --> $DIR/syntax-errors.rs:68:20
    |
 LL |         ${count($i a b c)}
    |                    ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:46:20
+  --> $DIR/syntax-errors.rs:68:20
    |
 LL |         ${count($i a b c)}
    |                    ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:48:23
+  --> $DIR/syntax-errors.rs:70:23
    |
 LL |         ${count($i, 1 a b c)}
    |                       ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:48:23
+  --> $DIR/syntax-errors.rs:70:23
    |
 LL |         ${count($i, 1 a b c)}
    |                       ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:50:21
+  --> $DIR/syntax-errors.rs:72:21
    |
 LL |         ${count($i) a b c}
    |                     ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:50:21
+  --> $DIR/syntax-errors.rs:72:21
    |
 LL |         ${count($i) a b c}
    |                     ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:53:22
+  --> $DIR/syntax-errors.rs:75:22
    |
 LL |         ${ignore($i) a b c}
    |                      ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:53:22
+  --> $DIR/syntax-errors.rs:75:22
    |
 LL |         ${ignore($i) a b c}
    |                      ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:55:21
+  --> $DIR/syntax-errors.rs:77:21
    |
 LL |         ${ignore($i a b c)}
    |                     ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:55:21
+  --> $DIR/syntax-errors.rs:77:21
    |
 LL |         ${ignore($i a b c)}
    |                     ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:58:19
+  --> $DIR/syntax-errors.rs:80:19
    |
 LL |         ${index() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:58:19
+  --> $DIR/syntax-errors.rs:80:19
    |
 LL |         ${index() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:60:19
+  --> $DIR/syntax-errors.rs:82:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:60:19
+  --> $DIR/syntax-errors.rs:82:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:63:19
+  --> $DIR/syntax-errors.rs:85:19
    |
 LL |         ${index() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:63:19
+  --> $DIR/syntax-errors.rs:85:19
    |
 LL |         ${index() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:65:19
+  --> $DIR/syntax-errors.rs:87:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:65:19
+  --> $DIR/syntax-errors.rs:87:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
 
 error: meta-variable expression depth must be a literal
-  --> $DIR/syntax-errors.rs:72:33
+  --> $DIR/syntax-errors.rs:94:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ index(IDX) } };
    |                                 ^^^^^
 
 error: meta-variables within meta-variable expressions must be referenced using a dollar sign
-  --> $DIR/syntax-errors.rs:78:11
+  --> $DIR/syntax-errors.rs:100:11
    |
 LL |         ${count(foo)}
    |           ^^^^^
 
 error: meta-variables within meta-variable expressions must be referenced using a dollar sign
-  --> $DIR/syntax-errors.rs:85:11
+  --> $DIR/syntax-errors.rs:107:11
    |
 LL |         ${ignore(bar)}
    |           ^^^^^^
 
 error: unrecognized meta-variable expression
-  --> $DIR/syntax-errors.rs:91:33
+  --> $DIR/syntax-errors.rs:113:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ aaaaaaaaaaaaaa(i) } };
    |                                 ^^^^^^^^^^^^^^ help: supported expressions are count, ignore, index and len
 
 error: expected identifier or string literal
-  --> $DIR/syntax-errors.rs:38:33
+  --> $DIR/syntax-errors.rs:38:14
+   |
+LL |     () => { ${} };
+   |              ^^
+
+error: expected identifier, found `"hi"`
+  --> $DIR/syntax-errors.rs:44:17
+   |
+LL |      () => { ${ "hi" } };
+   |                 ^^^^ help: try removing `"hi"`
+
+error: expected identifier or string literal
+  --> $DIR/syntax-errors.rs:60:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ {} } };
    |                                 ^^
 
-error: aborting due to 21 previous errors
+error: aborting due to 25 previous errors