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Diffstat (limited to 'compiler/rustc_error_codes/src/error_codes/E0493.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0493.md | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0493.md b/compiler/rustc_error_codes/src/error_codes/E0493.md new file mode 100644 index 000000000..e891129ef --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0493.md @@ -0,0 +1,42 @@ +A value with a custom `Drop` implementation may be dropped during const-eval. + +Erroneous code example: + +```compile_fail,E0493 +enum DropType { + A, +} + +impl Drop for DropType { + fn drop(&mut self) {} +} + +struct Foo { + field1: DropType, +} + +static FOO: Foo = Foo { field1: (DropType::A, DropType::A).1 }; // error! +``` + +The problem here is that if the given type or one of its fields implements the +`Drop` trait, this `Drop` implementation cannot be called within a const +context since it may run arbitrary, non-const-checked code. To prevent this +issue, ensure all values with a custom `Drop` implementation escape the +initializer. + +``` +enum DropType { + A, +} + +impl Drop for DropType { + fn drop(&mut self) {} +} + +struct Foo { + field1: DropType, +} + +static FOO: Foo = Foo { field1: DropType::A }; // We initialize all fields + // by hand. +``` |