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Upgrading darling 0.14 to 0.20

Breaking0.14.4 → 0.20.11Breaking5Platform1Deprecated1New15Changed4Fixed9

Full comparisonBack to darling
BreakingUpgrade verdict

5 breaking changes and a platform requirement change.

In plain terms
  • A method in the generic parameter helper was renamed.
  • Two types lost a trait implementation, so code relying on it must change.
  • Code that used the old nested attribute type must switch to darling's own type.
  • The old way of parsing macro arguments is replaced by a new parsing call.
Must act Top 5 of 7 that need code or config changes

Requires Rust 1.56 from 0.20.9 (none stated before).

Installs 25 packages in all (was 26).

What you must change

Breaking5
In GenericParamExt, as_lifetime_def is renamed to as_lifetime_param.
GenericParamExtas_lifetime_defas_lifetime_param
0.20.0GitHub ReleaseSummarizedView source
Flag and SpannedValue no longer implement syn::spanned::Spanned.
FlagSpannedValuesyn::spanned::Spanned
0.20.0GitHub ReleaseSummarizedView source
Replaces all occurrences of syn::NestedMeta with darling::ast::NestedMeta.
syn::NestedMetadarling::ast::NestedMeta
0.20.0GitHub ReleaseSummarizedView source
Provides a replacement for the deprecated AttributeArgs using NestedMeta::parse_meta_list.
AttributeArgsNestedMeta::parse_meta_listError::fromwrite_errors
0.20.0GitHub ReleaseSummarizedView source
In GenericParamExt, LifetimeDef is now LifetimeParam.
GenericParamExtLifetimeDefLifetimeParam
0.20.0GitHub ReleaseSummarizedView source
Platform1
The MSRV (minimum supported Rust version) is now 1.56, because of syn.
0.20.0GitHub ReleaseSummarizedView source

Deprecations to plan for

Deprecated1
Warns that fields expecting syn::Expr cannot accept a string literal due to preserved quoting behavior.
syn::Expr
0.20.0GitHub ReleaseSummarizedView source