Add ide-assist: generate_doc_cfg

crates/ide-assists/src/handlers/generate_doc_cfg.rs

@@ -0,0 +1,131 @@
+use ide_db::assists::GroupLabel;
+use syntax::{
+    NodeOrToken::{Node, Token},
+    T,
+    ast::{self, AstNode, edit_in_place::Indent, make},
+    syntax_editor::Position,
+};
+
+use crate::{AssistContext, AssistId, Assists};
+
+// Assist: generate_doc_cfg
+//
+// Generate a doc-cfg attribute from cfg attribute.
+//
+// ```
+// #[$0cfg(unix)]
+// pub struct Foo;
+// ```
+// ->
+// ```
+// #[cfg(unix)]
+// #[cfg_attr(docsrs, doc(cfg(unix)))]
+// pub struct Foo;
+// ```
+pub(crate) fn generate_doc_cfg(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let name = ctx.find_node_at_offset::<ast::Path>()?;
+    let attr = ast::Attr::cast(name.syntax().parent()?.parent()?)?;
+    let indent = attr.indent_level();
+
+    if attr.simple_name()? != "cfg" {
+        return None;
+    }
+
+    let target = attr.syntax().text_range();
+    let group = GroupLabel("Generate doc-cfg".to_owned());
+
+    for on in ["docsrs", "doc"] {
+        let doc_cfg = generate_doc_cfg_attribute(&attr, on)?;
+        acc.add_group(
+            &group,
+            AssistId::generate("generate_doc_cfg"),
+            format!("Generate `{on}(docsrs, doc(cfg(...)))` from cfg"),
+            target,
+            |builder| {
+                let mut edit = builder.make_editor(attr.syntax());
+
+                edit.insert_all(
+                    Position::after(attr.syntax()),
+                    vec![
+                        make::tokens::whitespace(&format!("\n{indent}")).into(),
+                        doc_cfg.syntax().clone().into(),
+                    ],
+                );
+
+                builder.add_file_edits(ctx.vfs_file_id(), edit);
+            },
+        );
+    }
+    Some(())
+}
+
+fn generate_doc_cfg_attribute(attr: &ast::Attr, on: &str) -> Option<ast::Attr> {
+    let cfg = attr.token_tree()?;
+    let is_inner_attr = attr.excl_token().is_some();
+
+    let cfg_attr = make::meta_token_tree(
+        ident_path("cfg_attr"),
+        make::token_tree(
+            T!['('],
+            [
+                Token(make::tokens::ident(on)),
+                Token(make::token(T![,])),
+                Token(make::tokens::single_space()),
+                Token(make::tokens::ident("doc")),
+                Node(make::token_tree(T!['('], [Token(make::tokens::ident("cfg")), Node(cfg)])),
+            ],
+        ),
+    );
+
+    if is_inner_attr {
+        Some(make::attr_inner(cfg_attr).clone_for_update())
+    } else {
+        Some(make::attr_outer(cfg_attr).clone_for_update())
+    }
+}
+
+fn ident_path(s: &str) -> ast::Path {
+    make::path_from_segments([make::path_segment(make::name_ref(s))], false)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tests::check_assist;
+
+    #[test]
+    fn test_generate_doc_cfg() {
+        check_assist(
+            generate_doc_cfg,
+            r#"
+                #[$0cfg(unix)]
+                pub struct Foo;
+            "#,
+            r#"
+                #[cfg(unix)]
+                #[cfg_attr(docsrs, doc(cfg(unix)))]
+                pub struct Foo;
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_generate_doc_cfg_in_mod() {
+        check_assist(
+            generate_doc_cfg,
+            r#"
+                mod foo {
+                    #[$0cfg(unix)]
+                    pub struct Foo;
+                }
+            "#,
+            r#"
+                mod foo {
+                    #[cfg(unix)]
+                    #[cfg_attr(docsrs, doc(cfg(unix)))]
+                    pub struct Foo;
+                }
+            "#,
+        );
+    }
+}

crates/ide-assists/src/lib.rs

@@ -160,6 +160,7 @@ mod handlers {
     mod generate_delegate_trait;
     mod generate_deref;
     mod generate_derive;
+    mod generate_doc_cfg;
     mod generate_documentation_template;
     mod generate_enum_is_method;
     mod generate_enum_projection_method;
@@ -293,6 +294,7 @@ mod handlers {
             generate_derive::generate_derive,
             generate_documentation_template::generate_doc_example,
             generate_documentation_template::generate_documentation_template,
+            generate_doc_cfg::generate_doc_cfg,
             generate_enum_is_method::generate_enum_is_method,
             generate_enum_projection_method::generate_enum_as_method,
             generate_enum_projection_method::generate_enum_try_into_method,

crates/ide-assists/src/tests/generated.rs

@@ -1540,6 +1540,22 @@ struct Point {
     )
 }
 
+#[test]
+fn doctest_generate_doc_cfg() {
+    check_doc_test(
+        "generate_doc_cfg",
+        r#####"
+#[$0cfg(unix)]
+pub struct Foo;
+"#####,
+        r#####"
+#[cfg(unix)]
+#[cfg_attr(docsrs, doc(cfg(unix)))]
+pub struct Foo;
+"#####,
+    )
+}
+
 #[test]
 fn doctest_generate_doc_example() {
     check_doc_test(