At least with Rust 1.66 / Cargo 1.66, embedded newlines are not permitted in inline tables in TOML. This is also noted in the TOML specification: "No newlines are allowed between the curly braces unless they are valid within a value." So it appears Cargo is simply enforcing the TOML specification.
The pre-book-release version of the Cargo.toml uses multiple TOML (non-inline) tables, which appears to be the recommended TOML formatting if you need to break the table over multiple lines.
For some (not documented in the commit) reason this was changed to a more "JSON-like" multiline inline structure with the release of the book. I'm unclear if there is any rust/cargo version where that multi-line structure of inline TOML tables ever worked, or if this is just another thing that was never tested prior to release.
It apears sufficient to simply join the whole {...} inline table in the TOML onto a single line, in each case.
Ewen
PS: Both the "smoltcp" and "trust-dns" dependency details got reformatted in the book release version of Cargo.toml; both will need fixing for cargo to accept the Cargo.toml file.
ewen@rustdev:~/misc/src/rust/rust-in-action/ch8/ch8-mget$ git status Cargo.toml
On branch 1st-edition
Your branch is up to date with 'origin/1st-edition'.
nothing to commit, working tree clean
ewen@rustdev:~/misc/src/rust/rust-in-action/ch8/ch8-mget$ grep -A 99 dependencies Cargo.toml
[dependencies]
clap = "2"
rand = "0.7"
smoltcp = {
version = "0.6",
features = ["proto-igmp", "proto-ipv4", "verbose", "log"]
}
trust-dns = {
version = "0.16",
default-features = false
}
url = "2"
ewen@rustdev:~/misc/src/rust/rust-in-action/ch8/ch8-mget$ cargo build
error: failed to parse manifest at `/home/ewen/misc/src/rust/rust-in-action/ch8/ch8-mget/Cargo.toml`
Caused by:
could not parse input as TOML
Caused by:
TOML parse error at line 10, column 12
|
10 | smoltcp = {
| ^
Unexpected `
`
Expected key
ewen@rustdev:~/misc/src/rust/rust-in-action/ch8/ch8-mget$
At least with Rust 1.66 / Cargo 1.66, embedded newlines are not permitted in inline tables in TOML. This is also noted in the TOML specification: "No newlines are allowed between the curly braces unless they are valid within a value." So it appears Cargo is simply enforcing the TOML specification.
The pre-book-release version of the Cargo.toml uses multiple TOML (non-inline) tables, which appears to be the recommended TOML formatting if you need to break the table over multiple lines.
For some (not documented in the commit) reason this was changed to a more "JSON-like" multiline inline structure with the release of the book. I'm unclear if there is any rust/cargo version where that multi-line structure of inline TOML tables ever worked, or if this is just another thing that was never tested prior to release.
It apears sufficient to simply join the whole
{...}inline table in the TOML onto a single line, in each case.Ewen
PS: Both the "smoltcp" and "trust-dns" dependency details got reformatted in the book release version of
Cargo.toml; both will need fixing for cargo to accept theCargo.tomlfile.