bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/diagnostics/expr.rs')
-rw-r--r--crates/hir-ty/src/diagnostics/expr.rs37
1 files changed, 34 insertions, 3 deletions
diff --git a/crates/hir-ty/src/diagnostics/expr.rs b/crates/hir-ty/src/diagnostics/expr.rs
index 0c5d639961..6c8a187516 100644
--- a/crates/hir-ty/src/diagnostics/expr.rs
+++ b/crates/hir-ty/src/diagnostics/expr.rs
@@ -12,6 +12,7 @@ use hir_expand::name;
use itertools::Itertools;
use rustc_hash::FxHashSet;
use rustc_pattern_analysis::usefulness::{compute_match_usefulness, ValidityConstraint};
+use syntax::{ast, AstNode};
use tracing::debug;
use triomphe::Arc;
use typed_arena::Arena;
@@ -108,7 +109,7 @@ impl ExprValidator {
self.check_for_trailing_return(*body_expr, &body);
}
Expr::If { .. } => {
- self.check_for_unnecessary_else(id, expr, &body);
+ self.check_for_unnecessary_else(id, expr, db);
}
Expr::Block { .. } => {
self.validate_block(db, expr);
@@ -336,12 +337,12 @@ impl ExprValidator {
}
}
- fn check_for_unnecessary_else(&mut self, id: ExprId, expr: &Expr, body: &Body) {
+ fn check_for_unnecessary_else(&mut self, id: ExprId, expr: &Expr, db: &dyn HirDatabase) {
if let Expr::If { condition: _, then_branch, else_branch } = expr {
if else_branch.is_none() {
return;
}
- if let Expr::Block { statements, tail, .. } = &body.exprs[*then_branch] {
+ if let Expr::Block { statements, tail, .. } = &self.body.exprs[*then_branch] {
let last_then_expr = tail.or_else(|| match statements.last()? {
Statement::Expr { expr, .. } => Some(*expr),
_ => None,
@@ -349,6 +350,36 @@ 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 })
}