Attribute values must be literals. The error you get when that doesn't
hold is pretty bad, e.g.:
```
unexpected expression: 1 + 1
```
You also get the same error if the attribute value is a literal, but an
invalid literal, e.g.:
```
unexpected expression: "foo"suffix
```
This commit does two things.
- Changes the error message to "attribute value must be a literal",
which gives a better idea of what the problem is and how to fix it. It
also no longer prints the invalid expression, because the carets below
highlight it anyway.
- Separates the "not a literal" case from the "invalid literal" case.
Which means invalid literals now get the specific error at the literal
level, rather than at the attribute level.
never_patterns: Parse match arms with no body
Never patterns are meant to signal unreachable cases, and thus don't take bodies:
```rust
let ptr: *const Option<!> = ...;
match *ptr {
None => { foo(); }
Some(!),
}
```
This PR makes rustc accept the above, and enforces that an arm has a body xor is a never pattern. This affects parsing of match arms even with the feature off, so this is delicate. (Plus this is my first non-trivial change to the parser).
~~The last commit is optional; it introduces a bit of churn to allow the new suggestions to be machine-applicable. There may be a better solution? I'm not sure.~~ EDIT: I removed that commit
r? `@compiler-errors`
Remove asmjs
Fulfills [MCP 668](https://github.com/rust-lang/compiler-team/issues/668).
`asmjs-unknown-emscripten` does not work as-specified, and lacks essential upstream support for generating asm.js, so it should not exist at all.
Give a better diagnostic for missing parens in Fn* bounds
Fixes#108109
It would be nice to try and recover here, but I'm not sure it's worth the effort, especially as the bounds on the recovered function would be incorrect.
Detect missing `=>` after match guard during parsing
```
error: expected one of `,`, `:`, or `}`, found `.`
--> $DIR/missing-fat-arrow.rs:25:14
|
LL | Some(a) if a.value == b {
| - while parsing this struct
LL | a.value = 1;
| -^ expected one of `,`, `:`, or `}`
| |
| while parsing this struct field
|
help: try naming a field
|
LL | a: a.value = 1;
| ++
help: you might have meant to start a match arm after the match guard
|
LL | Some(a) if a.value == b => {
| ++
```
Fix#78585.
```
error: expected one of `,`, `:`, or `}`, found `.`
--> $DIR/missing-fat-arrow.rs:25:14
|
LL | Some(a) if a.value == b {
| - while parsing this struct
LL | a.value = 1;
| -^ expected one of `,`, `:`, or `}`
| |
| while parsing this struct field
|
help: try naming a field
|
LL | a: a.value = 1;
| ++
help: you might have meant to start a match arm after the match guard
|
LL | Some(a) if a.value == b => {
| ++
```
Fix#78585.
