Auto merge of #57140 - estebank:str-err, r=varkor

Tweaks to format string diagnostics

Add label spans and fix incorrect spans.

Fix #55155, fix #55350.

7 files changed, 61 insertions, 37 deletions

diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index fc8325e5915..32ae878909f 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -144,7 +144,7 @@ pub struct Parser<'a> {
     /// `Some(raw count)` when the string is "raw", used to position spans correctly
     style: Option<usize>,
     /// Start and end byte offset of every successfully parsed argument
-    pub arg_places: Vec<(usize, usize)>,
+    pub arg_places: Vec<(SpanIndex, SpanIndex)>,
     /// Characters that need to be shifted
     skips: Vec<usize>,
     /// Span offset of the last opening brace seen, used for error reporting
@@ -154,7 +154,7 @@ pub struct Parser<'a> {
 }
 
 #[derive(Clone, Copy, Debug)]
-pub struct SpanIndex(usize);
+pub struct SpanIndex(pub usize);
 
 impl SpanIndex {
     pub fn unwrap(self) -> usize {
@@ -166,7 +166,6 @@ impl<'a> Iterator for Parser<'a> {
     type Item = Piece<'a>;
 
     fn next(&mut self) -> Option<Piece<'a>> {
-        let raw = self.raw();
         if let Some(&(pos, c)) = self.cur.peek() {
             match c {
                 '{' => {
@@ -180,7 +179,7 @@ impl<'a> Iterator for Parser<'a> {
                     } else {
                         let arg = self.argument();
                         if let Some(arg_pos) = self.must_consume('}').map(|end| {
-                            (pos + raw + 1, end + raw + 2)
+                            (self.to_span_index(pos), self.to_span_index(end + 1))
                         }) {
                             self.arg_places.push(arg_pos);
                         }
diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index 9d29e2b0fb6..95bb8c886ab 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -860,7 +860,9 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
     }
 
     let arg_spans = parser.arg_places.iter()
-        .map(|&(start, end)| fmt.span.from_inner_byte_pos(start, end))
+        .map(|&(parse::SpanIndex(start), parse::SpanIndex(end))| {
+            fmt.span.from_inner_byte_pos(start, end)
+        })
         .collect();
 
     let mut cx = Context {
@@ -954,13 +956,18 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
         let mut diag = {
             if errs_len == 1 {
                 let (sp, msg) = errs.into_iter().next().unwrap();
-                cx.ecx.struct_span_err(sp, msg)
+                let mut diag = cx.ecx.struct_span_err(sp, msg);
+                diag.span_label(sp, msg);
+                diag
             } else {
                 let mut diag = cx.ecx.struct_span_err(
                     errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
                     "multiple unused formatting arguments",
                 );
                 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
+                for (sp, msg) in errs {
+                    diag.span_label(sp, msg);
+                }
                 diag
             }
         };
diff --git a/src/test/ui/fmt/format-string-error-2.rs b/src/test/ui/fmt/format-string-error-2.rs
index fd6e41ec6fc..3c6c15c06bb 100644
--- a/src/test/ui/fmt/format-string-error-2.rs
+++ b/src/test/ui/fmt/format-string-error-2.rs
@@ -67,4 +67,6 @@ raw  { \n
     asdf}
     ", asdf=1);
     //~^^ ERROR invalid format string
+    println!("\t{}");
+    //~^ ERROR 1 positional argument in format string
 }
diff --git a/src/test/ui/fmt/format-string-error-2.stderr b/src/test/ui/fmt/format-string-error-2.stderr
index 0b3f08c1fbe..face0bc0f5f 100644
--- a/src/test/ui/fmt/format-string-error-2.stderr
+++ b/src/test/ui/fmt/format-string-error-2.stderr
@@ -133,5 +133,11 @@ LL |     asdf}
    |
    = note: if you intended to print `{`, you can escape it using `{{`
 
-error: aborting due to 13 previous errors
+error: 1 positional argument in format string, but no arguments were given
+  --> $DIR/format-string-error-2.rs:70:17
+   |
+LL |     println!("/t{}");
+   |                 ^^
+
+error: aborting due to 14 previous errors
 
diff --git a/src/test/ui/if/ifmt-bad-arg.stderr b/src/test/ui/if/ifmt-bad-arg.stderr
index 3ae8669a7f2..d4153ac94ac 100644
--- a/src/test/ui/if/ifmt-bad-arg.stderr
+++ b/src/test/ui/if/ifmt-bad-arg.stderr
@@ -16,7 +16,7 @@ error: argument never used
   --> $DIR/ifmt-bad-arg.rs:9:20
    |
 LL |     format!("{1}", 1);
-   |             -----  ^
+   |             -----  ^ argument never used
    |             |
    |             formatting specifier missing
 
@@ -80,15 +80,16 @@ error: multiple unused formatting arguments
   --> $DIR/ifmt-bad-arg.rs:32:17
    |
 LL |     format!("", 1, 2);               //~ ERROR: multiple unused formatting arguments
-   |             --  ^  ^
-   |             |
+   |             --  ^  ^ argument never used
+   |             |   |
+   |             |   argument never used
    |             multiple missing formatting specifiers
 
 error: argument never used
   --> $DIR/ifmt-bad-arg.rs:33:22
    |
 LL |     format!("{}", 1, 2);             //~ ERROR: argument never used
-   |             ----     ^
+   |             ----     ^ argument never used
    |             |
    |             formatting specifier missing
 
@@ -96,7 +97,7 @@ error: argument never used
   --> $DIR/ifmt-bad-arg.rs:34:20
    |
 LL |     format!("{1}", 1, 2);            //~ ERROR: argument never used
-   |             -----  ^
+   |             -----  ^ argument never used
    |             |
    |             formatting specifier missing
 
@@ -104,7 +105,7 @@ error: named argument never used
   --> $DIR/ifmt-bad-arg.rs:35:26
    |
 LL |     format!("{}", 1, foo=2);         //~ ERROR: named argument never used
-   |             ----         ^
+   |             ----         ^ named argument never used
    |             |
    |             formatting specifier missing
 
@@ -112,7 +113,7 @@ error: argument never used
   --> $DIR/ifmt-bad-arg.rs:36:22
    |
 LL |     format!("{foo}", 1, foo=2);      //~ ERROR: argument never used
-   |             -------  ^
+   |             -------  ^ argument never used
    |             |
    |             formatting specifier missing
 
@@ -120,7 +121,7 @@ error: named argument never used
   --> $DIR/ifmt-bad-arg.rs:37:21
    |
 LL |     format!("", foo=2);              //~ ERROR: named argument never used
-   |             --      ^
+   |             --      ^ named argument never used
    |             |
    |             formatting specifier missing
 
@@ -128,8 +129,9 @@ error: multiple unused formatting arguments
   --> $DIR/ifmt-bad-arg.rs:38:32
    |
 LL |     format!("{} {}", 1, 2, foo=1, bar=2);  //~ ERROR: multiple unused formatting arguments
-   |             -------            ^      ^
-   |             |
+   |             -------            ^      ^ named argument never used
+   |             |                  |
+   |             |                  named argument never used
    |             multiple missing formatting specifiers
 
 error: duplicate argument named `foo`
@@ -160,7 +162,7 @@ error: named argument never used
   --> $DIR/ifmt-bad-arg.rs:45:51
    |
 LL |     format!("{valuea} {valueb}", valuea=5, valuec=7);
-   |             -------------------                   ^
+   |             -------------------                   ^ named argument never used
    |             |
    |             formatting specifier missing
 
@@ -194,7 +196,7 @@ error: argument never used
   --> $DIR/ifmt-bad-arg.rs:56:27
    |
 LL |     format!("foo %s baz", "bar"); //~ ERROR: argument never used
-   |                  --       ^^^^^
+   |                  --       ^^^^^ argument never used
    |                  |
    |                  help: format specifiers use curly braces: `{}`
    |
diff --git a/src/test/ui/macros/format-foreign.stderr b/src/test/ui/macros/format-foreign.stderr
index 41c3c9d75c0..0b8bfcbdc17 100644
--- a/src/test/ui/macros/format-foreign.stderr
+++ b/src/test/ui/macros/format-foreign.stderr
@@ -2,8 +2,10 @@ error: multiple unused formatting arguments
   --> $DIR/format-foreign.rs:2:30
    |
 LL |     println!("%.*3$s %s!/n", "Hello,", "World", 4); //~ ERROR multiple unused formatting arguments
-   |              --------------  ^^^^^^^^  ^^^^^^^  ^
-   |              |
+   |              --------------  ^^^^^^^^  ^^^^^^^  ^ argument never used
+   |              |               |         |
+   |              |               |         argument never used
+   |              |               argument never used
    |              multiple missing formatting specifiers
    |
    = note: printf formatting not supported; see the documentation for `std::fmt`
@@ -16,7 +18,7 @@ error: argument never used
   --> $DIR/format-foreign.rs:3:29
    |
 LL |     println!("%1$*2$.*3$f", 123.456); //~ ERROR never used
-   |               -----------   ^^^^^^^
+   |               -----------   ^^^^^^^ argument never used
    |               |
    |               help: format specifiers use curly braces: `{0:1$.2$}`
    |
@@ -29,8 +31,10 @@ LL |       println!(r###"%.*3$s
    |  ______________-
 LL | |         %s!/n
 LL | | "###, "Hello,", "World", 4);
-   | |    -  ^^^^^^^^  ^^^^^^^  ^
-   | |____|
+   | |    -  ^^^^^^^^  ^^^^^^^  ^ argument never used
+   | |    |  |         |
+   | |    |  |         argument never used
+   | |____|  argument never used
    |      multiple missing formatting specifiers
    |
    = note: printf formatting not supported; see the documentation for `std::fmt`
@@ -44,7 +48,7 @@ error: argument never used
   --> $DIR/format-foreign.rs:12:30
    |
 LL |     println!("{} %f", "one", 2.0); //~ ERROR never used
-   |              -------         ^^^
+   |              -------         ^^^ argument never used
    |              |
    |              formatting specifier missing
 
@@ -52,7 +56,7 @@ error: named argument never used
   --> $DIR/format-foreign.rs:14:39
    |
 LL |     println!("Hi there, $NAME.", NAME="Tim"); //~ ERROR never used
-   |                         -----         ^^^^^
+   |                         -----         ^^^^^ named argument never used
    |                         |
    |                         help: format specifiers use curly braces: `{NAME}`
    |
@@ -62,8 +66,10 @@ error: multiple unused formatting arguments
   --> $DIR/format-foreign.rs:15:32
    |
 LL |     println!("$1 $0 $$ $NAME", 1, 2, NAME=3);
-   |              ----------------  ^  ^       ^
-   |              |
+   |              ----------------  ^  ^       ^ named argument never used
+   |              |                 |  |
+   |              |                 |  argument never used
+   |              |                 argument never used
    |              multiple missing formatting specifiers
    |
    = note: shell formatting not supported; see the documentation for `std::fmt`
diff --git a/src/test/ui/macros/format-unused-lables.stderr b/src/test/ui/macros/format-unused-lables.stderr
index c94ff2a1671..0a5e379a4ad 100644
--- a/src/test/ui/macros/format-unused-lables.stderr
+++ b/src/test/ui/macros/format-unused-lables.stderr
@@ -2,8 +2,10 @@ error: multiple unused formatting arguments
   --> $DIR/format-unused-lables.rs:2:22
    |
 LL |     println!("Test", 123, 456, 789);
-   |              ------  ^^^  ^^^  ^^^
-   |              |
+   |              ------  ^^^  ^^^  ^^^ argument never used
+   |              |       |    |
+   |              |       |    argument never used
+   |              |       argument never used
    |              multiple missing formatting specifiers
 
 error: multiple unused formatting arguments
@@ -12,17 +14,17 @@ error: multiple unused formatting arguments
 LL |     println!("Test2",
    |              ------- multiple missing formatting specifiers
 LL |         123,  //~ ERROR multiple unused formatting arguments
-   |         ^^^
+   |         ^^^ argument never used
 LL |         456,
-   |         ^^^
+   |         ^^^ argument never used
 LL |         789
-   |         ^^^
+   |         ^^^ argument never used
 
 error: named argument never used
   --> $DIR/format-unused-lables.rs:11:35
    |
 LL |     println!("Some stuff", UNUSED="args"); //~ ERROR named argument never used
-   |              ------------         ^^^^^^
+   |              ------------         ^^^^^^ named argument never used
    |              |
    |              formatting specifier missing
 
@@ -35,12 +37,12 @@ LL |     println!("Some more $STUFF",
    |              |          help: format specifiers use curly braces: `{STUFF}`
    |              multiple missing formatting specifiers
 LL |         "woo!",  //~ ERROR multiple unused formatting arguments
-   |         ^^^^^^
+   |         ^^^^^^ argument never used
 LL |             STUFF=
 LL |        "things"
-   |        ^^^^^^^^
+   |        ^^^^^^^^ named argument never used
 LL |              , UNUSED="args");
-   |                       ^^^^^^
+   |                       ^^^^^^ named argument never used
    |
    = note: shell formatting not supported; see the documentation for `std::fmt`