Skip to content

refactor(header): use better panic message in const HeaderName and HeaderValue #797

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
seanmonstar merged 1 commit into from
Nov 21, 2025
+3 −58
Merged

refactor(header): use better panic message in const HeaderName and HeaderValue #797

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 2 additions & 29 deletions src/header/name.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1205,27 +1205,6 @@ impl HeaderName {
///
/// This function panics when the static string is a invalid header.
///
/// Until [Allow panicking in constants](https://github.com/rust-lang/rfcs/pull/2345)
/// makes its way into stable, the panic message at compile-time is
/// going to look cryptic, but should at least point at your header value:
///
/// ```text
/// error: any use of this value will cause an error
/// --> http/src/header/name.rs:1241:13
/// |
/// 1241 | ([] as [u8; 0])[0]; // Invalid header name
/// | ^^^^^^^^^^^^^^^^^^
/// | |
/// | index out of bounds: the length is 0 but the index is 0
/// | inside `http::HeaderName::from_static` at http/src/header/name.rs:1241:13
/// | inside `INVALID_NAME` at src/main.rs:3:34
/// |
/// ::: src/main.rs:3:1
/// |
/// 3 | const INVALID_NAME: HeaderName = HeaderName::from_static("Capitalized");
/// | ------------------------------------------------------------------------
/// ```
///
/// # Examples
///
/// ```
Expand All @@ -1252,7 +1231,6 @@ impl HeaderName {
/// let a = HeaderName::from_static("foobar");
/// let b = HeaderName::from_static("FOOBAR"); // This line panics!
/// ```
#[allow(unconditional_panic)] // required for the panic circumvention
pub const fn from_static(src: &'static str) -> HeaderName {
let name_bytes = src.as_bytes();
if let Some(standard) = StandardHeader::from_bytes(name_bytes) {
Expand All @@ -1272,13 +1250,8 @@ impl HeaderName {
i += 1;
}
} {
// TODO: When msrv is bumped to larger than 1.57, this should be
// replaced with `panic!` macro.
// https://blog.rust-lang.org/2021/12/02/Rust-1.57.0.html#panic-in-const-contexts
//
// See the panics section of this method's document for details.
#[allow(clippy::no_effect, clippy::out_of_bounds_indexing)]
([] as [u8; 0])[0]; // Invalid header name
// Invalid header name
panic!("HeaderName::from_static with invalid bytes")
}

HeaderName {
Expand Down
30 changes: 1 addition & 29 deletions src/header/value.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,27 +51,6 @@ impl HeaderValue {
/// This function panics if the argument contains invalid header value
/// characters.
///
/// Until [Allow panicking in constants](https://github.com/rust-lang/rfcs/pull/2345)
/// makes its way into stable, the panic message at compile-time is
/// going to look cryptic, but should at least point at your header value:
///
/// ```text
/// error: any use of this value will cause an error
/// --> http/src/header/value.rs:67:17
/// |
/// 67 | ([] as [u8; 0])[0]; // Invalid header value
/// | ^^^^^^^^^^^^^^^^^^
/// | |
/// | index out of bounds: the length is 0 but the index is 0
/// | inside `HeaderValue::from_static` at http/src/header/value.rs:67:17
/// | inside `INVALID_HEADER` at src/main.rs:73:33
/// |
/// ::: src/main.rs:73:1
/// |
/// 73 | const INVALID_HEADER: HeaderValue = HeaderValue::from_static("жsome value");
/// | ----------------------------------------------------------------------------
/// ```
///
/// # Examples
///
/// ```
Expand All @@ -80,19 +59,12 @@ impl HeaderValue {
/// assert_eq!(val, "hello");
/// ```
#[inline]
#[allow(unconditional_panic)] // required for the panic circumvention
pub const fn from_static(src: &'static str) -> HeaderValue {
let bytes = src.as_bytes();
let mut i = 0;
while i < bytes.len() {
if !is_visible_ascii(bytes[i]) {
// TODO: When msrv is bumped to larger than 1.57, this should be
// replaced with `panic!` macro.
// https://blog.rust-lang.org/2021/12/02/Rust-1.57.0.html#panic-in-const-contexts
//
// See the panics section of this method's document for details.
#[allow(clippy::no_effect, clippy::out_of_bounds_indexing)]
([] as [u8; 0])[0]; // Invalid header value
panic!("HeaderValue::from_static with invalid bytes")
}
i += 1;
}
Expand Down