From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- .../rustc_error_codes/src/error_codes/E0502.md | 30 ++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 compiler/rustc_error_codes/src/error_codes/E0502.md (limited to 'compiler/rustc_error_codes/src/error_codes/E0502.md') 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 -- cgit v1.2.3