160 lines
3.2 KiB
Rust
160 lines
3.2 KiB
Rust
use crate::assist_context::{AssistContext, Assists};
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use ide_db::{
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assists::{AssistId, AssistKind},
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defs::Definition,
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LineIndexDatabase,
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};
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use syntax::{
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ast::{self, edit_in_place::Indent},
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AstNode,
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};
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// Assist: bind_unused_param
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//
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// Binds unused function parameter to an underscore.
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//
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// ```
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// fn some_function(x: i32$0) {}
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// ```
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// ->
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// ```
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// fn some_function(x: i32) {
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// let _ = x;
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// }
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// ```
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pub(crate) fn bind_unused_param(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
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let param: ast::Param = ctx.find_node_at_offset()?;
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let Some(ast::Pat::IdentPat(ident_pat)) = param.pat() else { return None };
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let param_def = {
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let local = ctx.sema.to_def(&ident_pat)?;
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Definition::Local(local)
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};
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if param_def.usages(&ctx.sema).at_least_one() {
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cov_mark::hit!(keep_used);
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return None;
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}
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let func = param.syntax().ancestors().find_map(ast::Fn::cast)?;
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let stmt_list = func.body()?.stmt_list()?;
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let l_curly_range = stmt_list.l_curly_token()?.text_range();
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let r_curly_range = stmt_list.r_curly_token()?.text_range();
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acc.add(
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AssistId("bind_unused_param", AssistKind::QuickFix),
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&format!("Bind as `let _ = {};`", &ident_pat),
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param.syntax().text_range(),
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|builder| {
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let line_index = ctx.db().line_index(ctx.file_id());
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let indent = func.indent_level();
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let text_indent = indent + 1;
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let mut text = format!("\n{text_indent}let _ = {ident_pat};");
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let left_line = line_index.line_col(l_curly_range.end()).line;
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let right_line = line_index.line_col(r_curly_range.start()).line;
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if left_line == right_line {
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cov_mark::hit!(single_line);
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text.push_str(&format!("\n{indent}"));
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}
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builder.insert(l_curly_range.end(), text);
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},
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)
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}
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#[cfg(test)]
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mod tests {
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use crate::tests::{check_assist, check_assist_not_applicable};
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use super::*;
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#[test]
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fn bind_unused_empty_block() {
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cov_mark::check!(single_line);
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check_assist(
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bind_unused_param,
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r#"
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fn foo($0y: i32) {}
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"#,
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r#"
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fn foo(y: i32) {
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let _ = y;
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}
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"#,
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);
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}
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#[test]
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fn bind_unused_empty_block_with_newline() {
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check_assist(
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bind_unused_param,
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r#"
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fn foo($0y: i32) {
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}
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"#,
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r#"
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fn foo(y: i32) {
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let _ = y;
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}
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"#,
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);
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}
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#[test]
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fn bind_unused_generic() {
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check_assist(
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bind_unused_param,
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r#"
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fn foo<T>($0y: T)
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where T : Default {
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}
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"#,
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r#"
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fn foo<T>(y: T)
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where T : Default {
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let _ = y;
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}
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"#,
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);
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}
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#[test]
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fn trait_impl() {
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check_assist(
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bind_unused_param,
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r#"
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trait Trait {
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fn foo(x: i32);
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}
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impl Trait for () {
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fn foo($0x: i32) {}
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}
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"#,
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r#"
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trait Trait {
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fn foo(x: i32);
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}
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impl Trait for () {
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fn foo(x: i32) {
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let _ = x;
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}
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}
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"#,
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);
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}
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#[test]
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fn keep_used() {
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cov_mark::check!(keep_used);
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check_assist_not_applicable(
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bind_unused_param,
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r#"
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fn foo(x: i32, $0y: i32) { y; }
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"#,
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);
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}
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}
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