For [E0308]: mismatched types, when expr is in an arm's body, not add… · rust-lang/rust@e8b5ba1 (original) (raw)
`@@ -27,10 +27,8 @@ use rustc_middle::lint::in_external_macro;
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`use rustc_middle::middle::stability::EvalResult;
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`use rustc_middle::span_bug;
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`use rustc_middle::ty::print::with_no_trimmed_paths;
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``
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use rustc_middle::ty::{
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``
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self, suggest_constraining_type_params, Article, Binder, IsSuggestable, Ty, TypeVisitableExt,
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``
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Upcast,
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``
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};
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`+
use rustc_middle::ty::{self, suggest_constraining_type_params, Article, Binder};
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use rustc_middle::ty::{IsSuggestable, Ty, TyCtxt, TypeVisitableExt, Upcast};
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`use rustc_session::errors::ExprParenthesesNeeded;
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`use rustc_span::source_map::Spanned;
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`use rustc_span::symbol::{sym, Ident};
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`@@ -1125,12 +1123,56 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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`self.tcx.hir().span_with_body(self.tcx.local_def_id_to_hir_id(fn_id)),
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`)
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`{
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err.multipart_suggestion(
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// When the expr is in a match arm's body, we shouldn't add semicolon ';' at the end.
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// For example:
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// fn mismatch_types() -> i32 {
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// match 1 {
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// x => dbg!(x),
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// }
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// todo!()
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// }
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// -------------^^^^^^^-
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// Don't add semicolon ; at the end of dbg!(x) expr
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fn is_in_arm<'tcx>(expr: &'tcx hir::Expr<'tcx>, tcx: TyCtxt<'tcx>) -> bool {
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for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
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match node {
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hir::Node::Block(block) => {
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if let Some(ret) = block.expr
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&& ret.hir_id == expr.hir_id
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{
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continue;
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}
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}
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hir::Node::Arm(arm) => {
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if let hir::ExprKind::Block(block, _) = arm.body.kind
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&& let Some(ret) = block.expr
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&& ret.hir_id == expr.hir_id
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{
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return true;
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}
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}
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hir::Node::Expr(e) if let hir::ExprKind::Block(block, _) = e.kind => {
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if let Some(ret) = block.expr
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&& ret.hir_id == expr.hir_id
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{
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continue;
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}
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}
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_ => {
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return false;
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}
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}
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}
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false
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}
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let mut suggs = vec![(span.shrink_to_lo(), "return ".to_string())];
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if !is_in_arm(expr, self.tcx) {
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suggs.push((span.shrink_to_hi(), ";".to_string()));
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}
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err.multipart_suggestion_verbose(
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`"you might have meant to return this value",
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vec![
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``
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(span.shrink_to_lo(), "return ".to_string()),
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``
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(span.shrink_to_hi(), ";".to_string()),
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``
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],
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suggs,
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`Applicability::MaybeIncorrect,
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`);
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`}
`