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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0128.md | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0128.md b/compiler/rustc_error_codes/src/error_codes/E0128.md new file mode 100644 index 000000000..2ea8ae68e --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0128.md @@ -0,0 +1,25 @@ +A type parameter with default value is using forward declared identifier. + +Erroneous code example: + +```compile_fail,E0128 +struct Foo<T = U, U = ()> { + field1: T, + field2: U, +} +// error: generic parameters with a default cannot use forward declared +// identifiers +``` + +Type parameter defaults can only use parameters that occur before them. Since +type parameters are evaluated in-order, this issue could be fixed by doing: + +``` +struct Foo<U = (), T = U> { + field1: T, + field2: U, +} +``` + +Please also verify that this wasn't because of a name-clash and rename the type +parameter if so. |