astgrep rule for turbopack

codemod_rewrite_vc_self.yml

language: rust
id: rewrite_vc_self
utils:
  self-await:
    pattern: self.await?
    not:  # there are no other ways self is used in this function
      inside:
        stopBy:
            kind: block
            inside:
              kind: function_item
              field: body
        has:
          kind: self
          stopBy:
            kind: impl_item
          not:
            inside:
              pattern: self.await?
              stopBy: end
  transparent-self:  # `self.await?` should rewrite to `&self.0`
    inside:
      kind: impl_item
      stopBy:
        kind: impl_item
      has:
        field: type
        pattern: $TYPE_NAME
        inside:
          kind: source_file
          stopBy: end
          has:
            kind: struct_item
            has:
              field: name
              pattern: $TYPE_NAME
            follows:
              pattern:
                context: |
                  #[turbo_tasks::value]
                selector: attribute_item
              stopBy:
                not:
                  kind: attribute_item
              has:
                kind: attribute
                has:
                  field: arguments
                  has:
                    pattern: transparent
  opaque-self:  # `self.await?` should rewrite to `&self`
    inside:
      kind: impl_item
      stopBy:
        kind: impl_item
      has:
        field: type
        pattern: $TYPE_NAME
        inside:
          kind: source_file
          stopBy: end
          has:
            kind: struct_item
            has:
              field: name
              pattern: $TYPE_NAME
            follows:
              pattern:
                context: |
                  #[turbo_tasks::value]
                selector: attribute_item
              stopBy:
                not:
                  kind: attribute_item
              not:
                has:
                  kind: attribute
                  has:
                    field: arguments
                    has:
                      pattern: transparent
  uses-readref-method:  # we'll conservatively bail out if we find any of these patterns
    has:
      stopBy:
        kind: impl_item
      any:
        - pattern: self.await?.clone_value
        - pattern: this.clone_value
        - pattern: ReadRef::cell
  passes-readref-by-value:  # we'll conservatively bail out if it looks like we might pass the readref by value
    has:
      stopBy:
        kind: impl_item
      any:
        - pattern: self.await?
        - pattern: this
      not:
        inside:
          any:
            - kind: reference_expression
            - kind: field_expression
            - kind: let_declaration  # N.B.: this is not entirely sound
            - kind: assignment_expression

rule:
  all:
    - pattern: $FUNC
    - kind: function_item
    - follows:
        pattern:
          context: |
            #[turbo_tasks::function]
          selector: attribute_item
        stopBy:
          not:
            kind: attribute_item
    - has:
        field: parameters
        has:
          pattern:
            selector: parameter
            context: |
              fn func(self: Vc<$_SELF_TY>) {}
    - has:
        field: body
        has:
          matches: self-await
          stopBy:
            kind: impl_item
    - any:  # if we can't tell if the struct is transparent or not, just bail out
      - matches: transparent-self
      - matches: opaque-self
    - not:
        any:
          - matches: uses-readref-method
          - matches: passes-readref-by-value


rewriters:
  - id: rewrite-self-await-opaque
    rule:
      all:
        - matches: self-await
        - matches: opaque-self
    fix:
      self

  - id: rewrite-self-await-transparent
    rule:
      all:
        - matches: self-await
        - matches: transparent-self
      any:
        - inside:
            kind: field_expression
            pattern: $$$
        - inside:
            kind: for_expression
            field: value
            has:
              pattern: "&self.await?"
            stopBy: end
        - pattern: $NEEDS_AMP  # only set this metavar if none of the above matches
    transform:
      MAYBE_AMP:
        replace:
          source: $NEEDS_AMP
          by: "&"
          replace: ".+"
    fix: "$MAYBE_AMPself.0"

  - id: rewrite-self-arg
    rule:
      pattern:
        selector: parameter
        context: |
          fn func(self: Vc<$_SELF_TY>) {}
    fix: "&self"

transform:
  NEW_FUNC:
    rewrite:
      source: $FUNC
      rewriters:
        - rewrite-self-await-opaque
        - rewrite-self-await-transparent
        - rewrite-self-arg

fix:
  $NEW_FUNC

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