Rollup merge of #52649 - estebank:fmt-span, r=oli-obk

Point spans to inner elements of format strings

- Point at missing positional specifiers in string literal
```
error: invalid reference to positional arguments 3, 4 and 5 (there are 3 arguments)
  --> $DIR/ifmt-bad-arg.rs:34:38
   |
LL |     format!("{name} {value} {} {} {} {} {} {}", 0, name=1, value=2);
   |                                      ^^ ^^ ^^
   |
   = note: positional arguments are zero-based
```

- Point at named formatting specifier in string literal
```
error: there is no argument named `foo`
  --> $DIR/ifmt-bad-arg.rs:37:17
   |
LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
   |                 ^^^^^
```

- Update label for formatting string in "multiple unused formatting arguments" to be more correct
```
error: multiple unused formatting arguments
  --> $DIR/ifmt-bad-arg.rs:42:17
   |
LL |     format!("", 1, 2);               //~ ERROR: multiple unused formatting arguments
   |             --  ^  ^
   |             |
   |             multiple missing formatting specifiers
```

- When using `printf` string formatting, provide a structured suggestion instead of a note
```
error: multiple unused formatting arguments
  --> $DIR/format-foreign.rs:12:30
   |
LL |     println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
   |              --------------  ^^^^^^^^  ^^^^^^^  ^
   |              |
   |              multiple missing formatting specifiers
   |
   = note: printf formatting not supported; see the documentation for `std::fmt`
help: format specifiers in Rust are written using `{}`
   |
LL |     println!("{:.2$} {}!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
   |               ^^^^^^ ^^
```

3 files changed, 43 insertions, 13 deletions

diff --git a/src/test/ui/macros/format-foreign.rs b/src/test/ui/macros/format-foreign.rs
index ec0eaed43ae..33401424c9a 100644
--- a/src/test/ui/macros/format-foreign.rs
+++ b/src/test/ui/macros/format-foreign.rs
@@ -11,6 +11,11 @@
 fn main() {
     println!("%.*3$s %s!\n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
     println!("%1$*2$.*3$f", 123.456); //~ ERROR never used
+    println!(r###"%.*3$s
+        %s!\n
+"###, "Hello,", "World", 4);
+    //~^ ERROR multiple unused formatting arguments
+    // correctly account for raw strings in inline suggestions
 
     // This should *not* produce hints, on the basis that there's equally as
     // many "correct" format specifiers.  It's *probably* just an actual typo.
diff --git a/src/test/ui/macros/format-foreign.stderr b/src/test/ui/macros/format-foreign.stderr
index 401b2f6d67e..5e76c0a322e 100644
--- a/src/test/ui/macros/format-foreign.stderr
+++ b/src/test/ui/macros/format-foreign.stderr
@@ -4,29 +4,52 @@ 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$}`
-   = help: `%s` should be written as `{}`
    = note: printf formatting not supported; see the documentation for `std::fmt`
+help: format specifiers use curly braces
+   |
+LL |     println!("{:.2$} {}!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
+   |               ^^^^^^ ^^
 
 error: argument never used
   --> $DIR/format-foreign.rs:13:29
    |
 LL |     println!("%1$*2$.*3$f", 123.456); //~ ERROR never used
-   |                             ^^^^^^^
+   |               -----------   ^^^^^^^
+   |               |
+   |               help: format specifiers use curly braces: `{0:1$.2$}`
    |
-   = help: `%1$*2$.*3$f` should be written as `{0:1$.2$}`
    = note: printf formatting not supported; see the documentation for `std::fmt`
 
+error: multiple unused formatting arguments
+  --> $DIR/format-foreign.rs:16:7
+   |
+LL |       println!(r###"%.*3$s
+   |  ______________-
+LL | |         %s!/n
+LL | | "###, "Hello,", "World", 4);
+   | |    -  ^^^^^^^^  ^^^^^^^  ^
+   | |____|
+   |      multiple missing formatting specifiers
+   |
+   = note: printf formatting not supported; see the documentation for `std::fmt`
+help: format specifiers use curly braces
+   |
+LL |     println!(r###"{:.2$}
+LL |         {}!/n
+   |
+
 error: argument never used
-  --> $DIR/format-foreign.rs:17:30
+  --> $DIR/format-foreign.rs:22:30
    |
 LL |     println!("{} %f", "one", 2.0); //~ ERROR never used
-   |                              ^^^
+   |              -------         ^^^
+   |              |
+   |              formatting specifier missing
 
 error: named argument never used
-  --> $DIR/format-foreign.rs:19:39
+  --> $DIR/format-foreign.rs:24:39
    |
 LL |     println!("Hi there, $NAME.", NAME="Tim"); //~ ERROR never used
    |                                       ^^^^^
@@ -34,5 +57,5 @@ LL |     println!("Hi there, $NAME.", NAME="Tim"); //~ ERROR never used
    = help: `$NAME` should be written as `{NAME}`
    = note: shell formatting not supported; see the documentation for `std::fmt`
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/macros/format-unused-lables.stderr b/src/test/ui/macros/format-unused-lables.stderr
index f764190438f..81171a1ed01 100644
--- a/src/test/ui/macros/format-unused-lables.stderr
+++ b/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,
@@ -22,13 +22,15 @@ error: named argument never used
   --> $DIR/format-unused-lables.rs:21:35
    |
 LL |     println!("Some stuff", UNUSED="args"); //~ ERROR named argument never used
-   |                                   ^^^^^^
+   |              ------------         ^^^^^^
+   |              |
+   |              formatting specifier missing
 
 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=