Point at formatting descriptor string when it is invalid
When a formatting string contains an invalid descriptor, point at it
instead of the argument:
```
error: unknown format trait `foo`
--> $DIR/ifmt-bad-arg.rs:86:17
|
LL | println!("{:foo}", 1);
| ^^^
|
= note: the only appropriate formatting traits are:
- ``, which uses the `Display` trait
- `?`, which uses the `Debug` trait
- `e`, which uses the `LowerExp` trait
- `E`, which uses the `UpperExp` trait
- `o`, which uses the `Octal` trait
- `p`, which uses the `Pointer` trait
- `b`, which uses the `Binary` trait
- `x`, which uses the `LowerHex` trait
- `X`, which uses the `UpperHex` trait
```
When a formatting string contains an invalid descriptor, point at it
instead of the argument:
```
error: unknown format trait `foo`
--> $DIR/ifmt-bad-arg.rs:86:17
|
LL | println!("{:foo}", 1);
| ^^^
|
= note: the only appropriate formatting traits are:
- ``, which uses the `Display` trait
- `?`, which uses the `Debug` trait
- `e`, which uses the `LowerExp` trait
- `E`, which uses the `UpperExp` trait
- `o`, which uses the `Octal` trait
- `p`, which uses the `Pointer` trait
- `b`, which uses the `Binary` trait
- `x`, which uses the `LowerHex` trait
- `X`, which uses the `UpperHex` trait
```
Increase spacing for suggestions in diagnostics
Make the spacing between the code snippet and verbose structured
suggestions consistent with note and help messages.
r? @Centril
Add secondary span labels with no text to make it clear when there's a
mismatch bewteen the positional arguments in a format string and the
arguments to the macro. This shouldn't affect experienced users, but it
should make it easier for newcomers to more clearly understand how
`format!()` and `println!()` are supposed to be used.
```
error: 2 positional arguments in format string, but there is 1 argument
--> file8.rs:2:14
|
2 | format!("{} {}", 1);
| ^^ ^^ -
```
instead of
```
error: 2 positional arguments in format string, but there is 1 argument
--> file8.rs:2:14
|
2 | format!("{} {}", 1);
| ^^ ^^
```
When positional width and precision formatting flags are present in a
formatting string that has an argument count mismatch, provide extra
information pointing at them making it easiser to understand where the
problem may lay:
```
error: 4 positional arguments in format string, but there are 3 arguments
--> $DIR/ifmt-bad-arg.rs:78:15
|
LL | println!("{} {:.*} {}", 1, 3.2, 4);
| ^^ ^^--^ ^^ --- this parameter corresponds to the precision flag
| |
| this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
|
= note: positional arguments are zero-based
= note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html
error: 4 positional arguments in format string, but there are 3 arguments
--> $DIR/ifmt-bad-arg.rs:81:15
|
LL | println!("{} {:07$.*} {}", 1, 3.2, 4);
| ^^ ^^-----^ ^^ --- this parameter corresponds to the precision flag
| | |
| | this precision flag adds an extra required argument at position 1, which is why there are 4 arguments expected
| this width flag expects an `usize` argument at position 7, but there are 3 arguments
|
= note: positional arguments are zero-based
= note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html
error: 3 positional arguments in format string, but there are 3 arguments
--> $DIR/ifmt-bad-arg.rs:84:15
|
LL | println!("{} {:07$} {}", 1, 3.2, 4);
| ^^ ^^---^ ^^
| |
| this width flag expects an `usize` argument at position 7, but there are 3 arguments
|
= note: positional arguments are zero-based
= note: for information about formatting flags, visit https://doc.rust-lang.org/std/fmt/index.html
```
Specific error for positional args after named args in `format!()`
When writing positional arguments after named arguments in the
`format!()` and `println!()` macros, provide a targeted diagnostic.
Follow up to https://github.com/rust-lang/rust/pull/57522/files#r247278885
Point at coercion reason for `if` expressions without else clause if caused by return type
```
error[E0317]: if may be missing an else clause
--> $DIR/if-without-else-as-fn-expr.rs:2:5
|
LL | fn foo(bar: usize) -> usize {
| ----- found `usize` because of this return type
LL | / if bar % 5 == 0 {
LL | | return 3;
LL | | }
| |_____^ expected (), found usize
|
= note: expected type `()`
found type `usize`
= note: `if` expressions without `else` must evaluate to `()`
```
Fix#25228.
```
error[E0317]: if may be missing an else clause
--> $DIR/if-without-else-as-fn-expr.rs:2:5
|
LL | fn foo(bar: usize) -> usize {
| ----- found `usize` because of this return type
LL | / if bar % 5 == 0 {
LL | | return 3;
LL | | }
| |_____^ expected (), found usize
|
= note: expected type `()`
found type `usize`
= note: `if` expressions without `else` must evaluate to `()`
```
- Point at the body expression of the match arm with the type error.
- Point at the prior match arms explicitely stating the evaluated type.
- Point at the entire match expr in a secondary span, instead of primary.
- For type errors in the first match arm, the cause is outside of the
match, treat as implicit block error to give a more appropriate error.
- Point at opening mismatched formatting brace
- Account for differences between raw and regular strings
- Account for differences between the code snippet and `InternedString`
- Add more tests
I also added `// skip-codegen` to each one, to address potential concerns
that this change would otherwise slow down our test suite spending time
generating code for files that are really just meant to be checks of
compiler diagnostics.
(However, I will say: My preference is to not use `// skip-codegen` if
one can avoid it. We can use all the testing of how we drive LLVM that
we can get...)
(Updated post rebase.)
