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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/E0004.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 '')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0004.md | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0004.md b/compiler/rustc_error_codes/src/error_codes/E0004.md new file mode 100644 index 000000000..b79ef5fd8 --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0004.md @@ -0,0 +1,46 @@ +This error indicates that the compiler cannot guarantee a matching pattern for +one or more possible inputs to a match expression. Guaranteed matches are +required in order to assign values to match expressions, or alternatively, +determine the flow of execution. + +Erroneous code example: + +```compile_fail,E0004 +enum Terminator { + HastaLaVistaBaby, + TalkToMyHand, +} + +let x = Terminator::HastaLaVistaBaby; + +match x { // error: non-exhaustive patterns: `HastaLaVistaBaby` not covered + Terminator::TalkToMyHand => {} +} +``` + +If you encounter this error you must alter your patterns so that every possible +value of the input type is matched. For types with a small number of variants +(like enums) you should probably cover all cases explicitly. Alternatively, the +underscore `_` wildcard pattern can be added after all other patterns to match +"anything else". Example: + +``` +enum Terminator { + HastaLaVistaBaby, + TalkToMyHand, +} + +let x = Terminator::HastaLaVistaBaby; + +match x { + Terminator::TalkToMyHand => {} + Terminator::HastaLaVistaBaby => {} +} + +// or: + +match x { + Terminator::TalkToMyHand => {} + _ => {} +} +``` |