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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_error_codes/src/error_codes/E0502.md | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_error_codes/src/error_codes/E0502.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0502.md | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0502.md b/compiler/rustc_error_codes/src/error_codes/E0502.md new file mode 100644 index 000000000..dc3ffdfdd --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0502.md @@ -0,0 +1,30 @@ +A variable already borrowed as immutable was borrowed as mutable. + +Erroneous code example: + +```compile_fail,E0502 +fn bar(x: &mut i32) {} +fn foo(a: &mut i32) { + let y = &a; // a is borrowed as immutable. + bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed + // as immutable + println!("{}", y); +} +``` + +To fix this error, ensure that you don't have any other references to the +variable before trying to access it mutably: + +``` +fn bar(x: &mut i32) {} +fn foo(a: &mut i32) { + bar(a); + let y = &a; // ok! + println!("{}", y); +} +``` + +For more information on Rust's ownership system, take a look at the +[References & Borrowing][references-and-borrowing] section of the Book. + +[references-and-borrowing]: https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html |