Change wording

compiler/rustc_ast_lowering/messages.ftl

@@ -5,7 +5,7 @@ ast_lowering_abi_specified_multiple_times =
 
 ast_lowering_arbitrary_expression_in_pattern =
     arbitrary expressions aren't allowed in patterns
-    .pattern_from_macro_note = the :expr fragment specifier forces the metavariable's content to be an expression
+    .pattern_from_macro_note = the `expr` fragment specifier forces the metavariable's content to be an expression
 
 ast_lowering_argument = argument
 

tests/ui/issues/issue-43250.stderr

@@ -4,15 +4,15 @@ error: arbitrary expressions aren't allowed in patterns
 LL |     m!(y);
    |        ^
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
 
 error: arbitrary expressions aren't allowed in patterns
   --> $DIR/issue-43250.rs:11:8
    |
 LL |     m!(C);
    |        ^
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
 
 error: aborting due to 2 previous errors
 

tests/ui/lowering/expr-in-pat-issue-99380.stderr

@@ -4,7 +4,7 @@ error: arbitrary expressions aren't allowed in patterns
 LL |     foo!(Some(3));
    |          ^^^^^^^
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
 
 error: aborting due to 1 previous error
 

tests/ui/macros/vec-macro-in-pattern.stderr

@@ -4,7 +4,7 @@ error: arbitrary expressions aren't allowed in patterns
 LL |         Some(vec![43]) => {}
    |              ^^^^^^^^
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
    = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error

tests/ui/match/expr_before_ident_pat.stderr

@@ -10,7 +10,7 @@ error: arbitrary expressions aren't allowed in patterns
 LL |     funny!(a, a);
    |            ^
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
 
 error: aborting due to 2 previous errors
 

tests/ui/pattern/issue-92074-macro-ice.stderr

@@ -7,7 +7,7 @@ LL |     () => { force_expr!(Vec::new()) }
 LL |     assert!(matches!(x, En::A(make_vec!())));
    |                               ----------- in this macro invocation
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
    = note: this error originates in the macro `make_vec` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: arbitrary expressions aren't allowed in patterns
@@ -19,7 +19,7 @@ LL |     () => { force_pat!(get_usize(), get_usize()) }
 LL |     assert!(matches!(5, make_pat!()));
    |                         ----------- in this macro invocation
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
    = note: this error originates in the macro `make_pat` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: arbitrary expressions aren't allowed in patterns
@@ -31,7 +31,7 @@ LL |     () => { force_pat!(get_usize(), get_usize()) }
 LL |     assert!(matches!(5, make_pat!()));
    |                         ----------- in this macro invocation
    |
-   = note: the :expr fragment specifier forces the metavariable's content to be an expression
+   = note: the `expr` fragment specifier forces the metavariable's content to be an expression
    = note: this error originates in the macro `make_pat` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 3 previous errors