Reword missing formatting arguments label

Author: estebank

src/libsyntax_ext/format.rs

@@ -928,7 +928,7 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
                     errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
                     "multiple unused formatting arguments",
                 );
-                diag.span_label(cx.fmtsp, "multiple missing formatting arguments");
+                diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
                 diag
             }
         };

src/test/ui/ifmt-bad-arg.stderr

@@ -80,7 +80,7 @@ error: multiple unused formatting arguments
 LL |     format!("", 1, 2);               //~ ERROR: multiple unused formatting arguments
    |             --  ^  ^
    |             |
-   |             multiple missing formatting arguments
+   |             multiple missing formatting specifiers
 
 error: argument never used
   --> $DIR/ifmt-bad-arg.rs:43:22
@@ -118,7 +118,7 @@ error: multiple unused formatting arguments
 LL |     format!("{} {}", 1, 2, foo=1, bar=2);  //~ ERROR: multiple unused formatting arguments
    |             -------            ^      ^
    |             |
-   |             multiple missing formatting arguments
+   |             multiple missing formatting specifiers
 
 error: duplicate argument named `foo`
   --> $DIR/ifmt-bad-arg.rs:50:33

src/test/ui/macros/format-foreign.stderr

@@ -4,7 +4,7 @@ error: multiple unused formatting arguments
 LL |     println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
    |              --------------  ^^^^^^^^  ^^^^^^^  ^
    |              |
-   |              multiple missing formatting arguments
+   |              multiple missing formatting specifiers
    |
    = help: `%.*3$s` should be written as `{:.2$}`
    = help: `%s` should be written as `{}`

src/test/ui/macros/format-unused-lables.stderr

@@ -4,13 +4,13 @@ error: multiple unused formatting arguments
 LL |     println!("Test", 123, 456, 789);
    |              ------  ^^^  ^^^  ^^^
    |              |
-   |              multiple missing formatting arguments
+   |              multiple missing formatting specifiers
 
 error: multiple unused formatting arguments
   --> $DIR/format-unused-lables.rs:16:9
    |
 LL |     println!("Test2",
-   |              ------- multiple missing formatting arguments
+   |              ------- multiple missing formatting specifiers
 LL |         123,  //~ ERROR multiple unused formatting arguments
    |         ^^^
 LL |         456,
@@ -28,7 +28,7 @@ error: multiple unused formatting arguments
   --> $DIR/format-unused-lables.rs:24:9
    |
 LL |     println!("Some more $STUFF",
-   |              ------------------ multiple missing formatting arguments
+   |              ------------------ multiple missing formatting specifiers
 LL |         "woo!",  //~ ERROR multiple unused formatting arguments
    |         ^^^^^^
 LL |             STUFF=