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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/E0644.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/E0644.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0644.md | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0644.md b/compiler/rustc_error_codes/src/error_codes/E0644.md new file mode 100644 index 000000000..8c68da3b2 --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0644.md @@ -0,0 +1,29 @@ +A closure or generator was constructed that references its own type. + +Erroneous code example: + +```compile_fail,E0644 +fn fix<F>(f: &F) + where F: Fn(&F) +{ + f(&f); +} + +fn main() { + fix(&|y| { + // Here, when `x` is called, the parameter `y` is equal to `x`. + }); +} +``` + +Rust does not permit a closure to directly reference its own type, +either through an argument (as in the example above) or by capturing +itself through its environment. This restriction helps keep closure +inference tractable. + +The easiest fix is to rewrite your closure into a top-level function, +or into a method. In some cases, you may also be able to have your +closure call itself by capturing a `&Fn()` object or `fn()` pointer +that refers to itself. That is permitting, since the closure would be +invoking itself via a virtual call, and hence does not directly +reference its own *type*. |