Apply field doc-comments to builder methods

examples/example.rs

@@ -2,12 +2,17 @@ use typed_builder::TypedBuilder;
 
 #[derive(Debug, PartialEq, TypedBuilder)]
 struct Foo {
- // Mandatory Field:
+ /// `x` value.
+ ///
+ /// This field is mandatory.
  x: i32,
 
  // #[builder(default)] without parameter - use the type's default
  // #[builder(setter(strip_option))] - wrap the setter argument with `Some(...)`
- #[builder(default, setter(strip_option))]
+ #[builder(
+ default,
+ setter(strip_option, doc = "Set `y`. If you don't specify a value it'll default to no value.",)
+ )]
  y: Option<i32>,
 
  // Or you can set the default

tests/no_std.rs

@@ -52,10 +52,13 @@ fn test_into() {
 fn test_default() {
  #[derive(PartialEq, TypedBuilder)]
  struct Foo {
+ /// x value.
  #[builder(default, setter(strip_option))]
  x: Option<i32>,
  #[builder(default = 10)]
+ /// y value.
  y: i32,
+ /// z value.
  #[builder(default = [20, 30, 40])]
  z: [i32; 3],
  }

typed-builder-macro/src/field_info.rs

@@ -115,6 +115,7 @@ pub struct FieldBuilderAttr<'a> {
  pub default: Option<syn::Expr>,
  pub via_mutators: Option<ViaMutators>,
  pub deprecated: Option<&'a syn::Attribute>,
+ pub doc_comments: Vec<&'a syn::Expr>,
  pub setter: SetterSettings,
  /// Functions that are able to mutate fields in the builder that are already set
  pub mutators: Vec<Mutator>,
@@ -153,10 +154,20 @@ impl<'a> FieldBuilderAttr<'a> {
 
  list
  }
- syn::Meta::Path(path) | syn::Meta::NameValue(syn::MetaNameValue { path, .. }) => {
- if path_to_single_string(path).as_deref() == Some("deprecated") {
- self.deprecated = Some(attr);
- };
+ syn::Meta::NameValue(syn::MetaNameValue { path, value, .. }) => {
+ match path_to_single_string(path).as_deref() {
+ Some("deprecated") => self.deprecated = Some(attr),
+ Some("doc") => self.doc_comments.push(value),
+ _ => continue,
+ }
+
+ continue;
+ }
+ syn::Meta::Path(path) => {
+ match path_to_single_string(path).as_deref() {
+ Some("deprecated") => self.deprecated = Some(attr),
+ _ => continue,
+ }
 
  continue;
  }

typed-builder-macro/src/struct_info.rs

@@ -251,11 +251,25 @@ impl<'a> StructInfo<'a> {
  target_generics.push(syn::GenericArgument::Type(target_generics_tuple.into()));
  ty_generics.push(syn::GenericArgument::Type(ty_generics_tuple.into()));
  let (impl_generics, _, where_clause) = generics.split_for_impl();
- let doc = field.builder_attr.setter.doc.as_ref().map(|doc| quote!(#[doc = #doc]));
+ let doc = if let Some(doc) = field.builder_attr.setter.doc.as_ref() {
+ Some(quote!(#[doc = #doc]))
+ } else if !field.builder_attr.doc_comments.is_empty() {
+ Some(
+ field
+ .builder_attr
+ .doc_comments
+ .iter()
+ .map(|&line| quote!(#[doc = #line]))
+ .collect(),
+ )
+ } else {
+ None
+ };
+
  let deprecated = &field.builder_attr.deprecated;
 
  // NOTE: both auto_into and strip_option affect `arg_type` and `arg_expr`, but the order of
- // nesting is different so we have to do this little dance.
+ // nesting is different, so we have to do this little dance.
  let arg_type = if field.builder_attr.setter.strip_option.is_some() && field.builder_attr.setter.transform.is_none() {
  field
  .type_from_inside_option()
@@ -320,6 +334,7 @@ impl<'a> StructInfo<'a> {
  #[deprecated(
  note = #repeated_fields_error_message
  )]
+ #doc
  pub fn #method_name (self, _: #repeated_fields_error_type_name) -> #builder_name <#target_generics> {
  self
  }
@@ -354,8 +369,8 @@ impl<'a> StructInfo<'a> {
  let mut generics = self.generics.clone();
  for f in self.included_fields() {
  if f.builder_attr.default.is_some() || f.builder_attr.via_mutators.is_some() {
- // `f` is not mandatory - it does not have it's own fake `build` method, so `field` will need
- // to warn about missing `field` whether or not `f` is set.
+ // `f` is not mandatory - it does not have its own fake `build` method, so `field` will need
+ // to warn about missing `field` regardless of whether `f` is set.
  assert!(
  f.ordinal != field.ordinal,
  "`required_field_impl` called for optional field {}",