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fix: only emit "unnecessary else" diagnostic for expr stmts

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This commit is contained in:
davidsemakula 2024-02-16 20:39:52 +03:00
parent 1205853c36
commit ff70310086
2 changed files with 49 additions and 29 deletions
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64
crates/hir-ty/src/diagnostics/expr.rs
View File

@ -109,7 +109,7 @@ impl ExprValidator {
self.check_for_trailing_return(*body_expr, &body);
}
Expr::If { .. } => {
self.check_for_unnecessary_else(id, expr, db);
self.check_for_unnecessary_else(id, expr, &body, db);
}
Expr::Block { .. } => {
self.validate_block(db, expr);
@ -337,35 +337,17 @@ impl ExprValidator {
}
}
fn check_for_unnecessary_else(&mut self, id: ExprId, expr: &Expr, db: &dyn HirDatabase) {
fn check_for_unnecessary_else(
&mut self,
id: ExprId,
expr: &Expr,
body: &Body,
db: &dyn HirDatabase,
) {
if let Expr::If { condition: _, then_branch, else_branch } = expr {
if else_branch.is_none() {
return;
}
let (body, source_map) = db.body_with_source_map(self.owner);
let Ok(source_ptr) = source_map.expr_syntax(id) else {
return;
};
let root = source_ptr.file_syntax(db.upcast());
let ast::Expr::IfExpr(if_expr) = source_ptr.value.to_node(&root) else {
return;
};
let mut top_if_expr = if_expr;
loop {
let parent = top_if_expr.syntax().parent();
let has_parent_let_stmt =
parent.as_ref().map_or(false, |node| ast::LetStmt::can_cast(node.kind()));
if has_parent_let_stmt {
// Bail if parent or direct ancestor is a let stmt.
return;
}
let Some(parent_if_expr) = parent.and_then(ast::IfExpr::cast) else {
// Parent is neither an if expr nor a let stmt.
break;
};
// Check parent if expr.
top_if_expr = parent_if_expr;
}
if let Expr::Block { statements, tail, .. } = &body.exprs[*then_branch] {
let last_then_expr = tail.or_else(|| match statements.last()? {
Statement::Expr { expr, .. } => Some(*expr),
@ -374,6 +356,36 @@ impl ExprValidator {
if let Some(last_then_expr) = last_then_expr {
let last_then_expr_ty = &self.infer[last_then_expr];
if last_then_expr_ty.is_never() {
// Only look at sources if the then branch diverges and we have an else branch.
let (_, source_map) = db.body_with_source_map(self.owner);
let Ok(source_ptr) = source_map.expr_syntax(id) else {
return;
};
let root = source_ptr.file_syntax(db.upcast());
let ast::Expr::IfExpr(if_expr) = source_ptr.value.to_node(&root) else {
return;
};
let mut top_if_expr = if_expr;
loop {
let parent = top_if_expr.syntax().parent();
let has_parent_expr_stmt_or_stmt_list =
parent.as_ref().map_or(false, |node| {
ast::ExprStmt::can_cast(node.kind())
| ast::StmtList::can_cast(node.kind())
});
if has_parent_expr_stmt_or_stmt_list {
// Only emit diagnostic if parent or direct ancestor is either
// an expr stmt or a stmt list.
break;
}
let Some(parent_if_expr) = parent.and_then(ast::IfExpr::cast) else {
// Bail if parent is neither an if expr, an expr stmt nor a stmt list.
return;
};
// Check parent if expr.
top_if_expr = parent_if_expr;
}
self.diagnostics
.push(BodyValidationDiagnostic::RemoveUnnecessaryElse { if_expr: id })
}

14
crates/ide-diagnostics/src/handlers/remove_unnecessary_else.rs
View File

@ -467,10 +467,10 @@ fn test() {
}
#[test]
fn no_diagnostic_if_tail_exists_in_else_branch() {
fn no_diagnostic_if_not_expr_stmt() {
check_diagnostics_with_needless_return_disabled(
r#"
fn test1(a: bool) {
fn test1() {
let _x = if a {
return;
} else {
@ -478,7 +478,7 @@ fn test1(a: bool) {
};
}
fn test2(a: bool, b: bool, c: bool) {
fn test2() {
let _x = if a {
return;
} else if b {
@ -491,5 +491,13 @@ fn test2(a: bool, b: bool, c: bool) {
}
"#,
);
check_diagnostics_with_disabled(
r#"
fn test3() {
foo(if a { return 1 } else { 0 })
}
"#,
std::iter::once("E0308".to_owned()),
);
}
}