bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Write docs for lint / fix review nit

Browse source
This commit is contained in:
Nathan Whitaker 2020-09-22 11:20:06 -04:00
parent 1bcd2452fe
commit 576eb2a30c
4 changed files with 25 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

22
compiler/rustc_lint/src/methods.rs
View file

@ -6,6 +6,25 @@ use rustc_middle::ty;
use rustc_span::{symbol::sym, ExpnKind, Span};
declare_lint! {
/// The `temporary_cstring_as_ptr` lint detects getting the inner pointer of
/// a temporary `CString`.
///
/// ### Example
///
/// ```rust
/// # #![allow(unused)]
/// let c_str = CString::new("foo").unwrap().as_ptr();
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// The inner pointer of a `CString` lives only as long as the `CString` it
/// points to. Getting the inner pointer of a *temporary* `CString` allows the `CString`
/// to be dropped at the end of the statement, as it is not being referenced as far as the typesystem
/// is concerned. This means outside of the statement the pointer will point to freed memory, which
/// causes undefined behavior if the pointer is later dereferenced.
pub TEMPORARY_CSTRING_AS_PTR,
Warn,
"detects getting the inner pointer of a temporary `CString`"
@ -75,8 +94,7 @@ fn lint_cstring_as_ptr(
unwrap.span,
"this `CString` is deallocated at the end of the statement, bind it to a variable to extend its lifetime",
);
diag.note("pointers do not have a lifetime; when calling `as_ptr` the `CString` will be deallocated at the end of the statement...");
diag.note("...because nothing is referencing it as far as the type system is concerned");
diag.note("pointers do not have a lifetime; when calling `as_ptr` the `CString` will be deallocated at the end of the statement because nothing is referencing it as far as the type system is concerned");
diag.help("for more information, see https://doc.rust-lang.org/reference/destructors.html");
diag.emit();
});