Refactor sugg builder in unnecessary_fallible_conversions

Author: roife

clippy_lints/src/methods/unnecessary_fallible_conversions.rs

@@ -10,17 +10,64 @@ use rustc_span::{sym, Span};
 
 use super::UNNECESSARY_FALLIBLE_CONVERSIONS;
 
+#[derive(Copy, Clone)]
+enum SpansKind {
+ TraitFn { trait_span: Span, fn_span: Span },
+ Fn { fn_span: Span },
+}
+
 /// What function is being called and whether that call is written as a method call or a function
 /// call
-#[derive(Clone)]
+#[derive(Copy, Clone)]
 #[expect(clippy::enum_variant_names)]
 enum FunctionKind {
  /// `T::try_from(U)`
- TryFromFunction(Option<Vec<Span>>),
+ TryFromFunction(Option<SpansKind>),
  /// `t.try_into()`
  TryIntoMethod,
  /// `U::try_into(t)`
- TryIntoFunction(Option<Vec<Span>>),
+ TryIntoFunction(Option<SpansKind>),
+}
+
+impl FunctionKind {
+ fn applicability(&self, parent_unwrap_call: &Option<Span>) -> Applicability {
+ if parent_unwrap_call.is_none() {
+ return Applicability::Unspecified;
+ }
+ match &self {
+ FunctionKind::TryFromFunction(None) | FunctionKind::TryIntoFunction(None) => Applicability::Unspecified,
+ _ => Applicability::MachineApplicable,
+ }
+ }
+
+ fn default_sugg(&self, primary_span: Span) -> Vec<(Span, String)> {
+ match *self {
+ FunctionKind::TryFromFunction(_) => vec![(primary_span, String::from("From::from"))],
+ FunctionKind::TryIntoFunction(_) => vec![(primary_span, String::from("Into::into"))],
+ FunctionKind::TryIntoMethod => vec![(primary_span, String::from("into"))],
+ }
+ }
+
+ fn machine_applicable_sugg(&self, primary_span: Span, unwrap_span: Span) -> Vec<(Span, String)> {
+ let mut sugg = match *self {
+ FunctionKind::TryFromFunction(Some(spans)) => match spans {
+ SpansKind::TraitFn { trait_span, fn_span } => {
+ vec![(trait_span, String::from("From")), (fn_span, String::from("from"))]
+ },
+ SpansKind::Fn { fn_span } => vec![(fn_span, String::from("from"))],
+ },
+ FunctionKind::TryIntoFunction(Some(spans)) => match spans {
+ SpansKind::TraitFn { trait_span, fn_span } => {
+ vec![(trait_span, String::from("Into")), (fn_span, String::from("into"))]
+ },
+ SpansKind::Fn { fn_span } => vec![(fn_span, String::from("into"))],
+ },
+ FunctionKind::TryIntoMethod => vec![(primary_span, String::from("into"))],
+ _ => unreachable!(),
+ };
+ sugg.push((unwrap_span, String::new()));
+ sugg
+ }
 }
 
 fn check<'tcx>(
@@ -69,47 +116,17 @@ fn check<'tcx>(
  primary_span
  };
 
- let (source_ty, target_ty, sugg, applicability) = match (kind, parent_unwrap_call) {
- (FunctionKind::TryIntoMethod, Some(unwrap_span)) => {
- let sugg = vec![(primary_span, String::from("into")), (unwrap_span, String::new())];
- (self_ty, other_ty, sugg, Applicability::MachineApplicable)
- },
- (FunctionKind::TryFromFunction(Some(spans)), Some(unwrap_span)) => {
- let sugg = match spans.len() {
- 1 => vec![(spans[0], String::from("from")), (unwrap_span, String::new())],
- 2 => vec![
- (spans[0], String::from("From")),
- (spans[1], String::from("from")),
- (unwrap_span, String::new()),
- ],
- _ => unreachable!(),
- };
- (other_ty, self_ty, sugg, Applicability::MachineApplicable)
- },
- (FunctionKind::TryIntoFunction(Some(spans)), Some(unwrap_span)) => {
- let sugg = match spans.len() {
- 1 => vec![(spans[0], String::from("into")), (unwrap_span, String::new())],
- 2 => vec![
- (spans[0], String::from("Into")),
- (spans[1], String::from("into")),
- (unwrap_span, String::new()),
- ],
- _ => unreachable!(),
- };
- (self_ty, other_ty, sugg, Applicability::MachineApplicable)
- },
- (FunctionKind::TryFromFunction(_), _) => {
- let sugg = vec![(primary_span, String::from("From::from"))];
- (other_ty, self_ty, sugg, Applicability::Unspecified)
- },
- (FunctionKind::TryIntoFunction(_), _) => {
- let sugg = vec![(primary_span, String::from("Into::into"))];
- (self_ty, other_ty, sugg, Applicability::Unspecified)
- },
- (FunctionKind::TryIntoMethod, _) => {
- let sugg = vec![(primary_span, String::from("into"))];
- (self_ty, other_ty, sugg, Applicability::Unspecified)
- },
+ let (source_ty, target_ty) = match kind {
+ FunctionKind::TryIntoMethod | FunctionKind::TryIntoFunction(_) => (self_ty, other_ty),
+ FunctionKind::TryFromFunction(_) => (other_ty, self_ty),
+ };
+
+ let applicability = kind.applicability(&parent_unwrap_call);
+
+ let sugg = if applicability == Applicability::MachineApplicable {
+ kind.machine_applicable_sugg(primary_span, parent_unwrap_call.unwrap())
+ } else {
+ kind.default_sugg(primary_span)
  };
 
  span_lint_and_then(
@@ -151,10 +168,18 @@ pub(super) fn check_function(cx: &LateContext<'_>, expr: &Expr<'_>, callee: &Exp
  {
  let qpath_spans = match qpath {
  QPath::Resolved(_, path) => {
- let segments = path.segments.iter().map(|seg| seg.ident).collect::<Vec<_>>();
- (segments.len() == 2).then(|| vec![segments[0].span, segments[1].span])
+ if let [trait_seg, fn_seg] = path.segments {
+ Some(SpansKind::TraitFn {
+ trait_span: trait_seg.ident.span,
+ fn_span: fn_seg.ident.span,
+ })
+ } else {
+ None
+ }
  },
- QPath::TypeRelative(_, seg) => Some(vec![seg.ident.span]),
+ QPath::TypeRelative(_, seg) => Some(SpansKind::Fn {
+ fn_span: seg.ident.span,
+ }),
  QPath::LangItem(_, _) => unreachable!("`TryFrom` and `TryInto` are not lang items"),
  };