Detect Python-style f-string debug syntax in format strings and emit a
clear diagnostic explaining that it is not supported in Rust. When the
intended operation can be inferred, suggest the corresponding Rust
alternative e.g from `println!("{=}", x)` to `dbg!({x})`.
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Detect Python-style numeric grouping syntax in format strings (e.g. `{x:,}`)
and emit a clear diagnostic explaining that it is not supported in Rust.
This helps users coming from Python understand the error without exposing
the full set of valid Rust format specifiers.
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Detect the `{ident?}` pattern where `?` is immediately followed by `}` and emit
a clearer diagnostic explaining that `:` is required for Debug formatting.
This avoids falling back to a generic “invalid format string” error and adds
a targeted UI test for the case.
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Usman Akinyemi