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Auto merge of #12070 - roife:fix/issue-12034, r=Centri3
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Fix issue #12034: add autofixes for unnecessary_fallible_conversions

fixes #12034

Currently, the `unnecessary_fallible_conversions` lint was capable of autofixing expressions like `0i32.try_into().unwrap()`. However, it couldn't autofix expressions in the form of `i64::try_from(0i32).unwrap()` or `<i64 as TryFrom<i32>>::try_from(0).unwrap()`.

This pull request extends the functionality to correctly autofix these latter forms as well.

changelog: [`unnecessary_fallible_conversions`]: Add autofixes for more forms
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@bors
bors committed Feb 9, 2024
2 parents fb398a5 + 3c76b2c commit 28443e6
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Showing 4 changed files with 293 additions and 46 deletions.
141 changes: 100 additions & 41 deletions clippy_lints/src/methods/unnecessary_fallible_conversions.rs
View file
Expand Up @@ -2,25 +2,79 @@ use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::get_parent_expr;
use clippy_utils::ty::implements_trait;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_hir::{Expr, ExprKind, QPath};
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_middle::ty::print::with_forced_trimmed_paths;
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(Copy, Clone)]
#[expect(clippy::enum_variant_names)]
enum FunctionKind {
/// `T::try_from(U)`
TryFromFunction,
TryFromFunction(Option<SpansKind>),
/// `t.try_into()`
TryIntoMethod,
/// `U::try_into(t)`
TryIntoFunction,
TryIntoFunction(Option<SpansKind>),
}

impl FunctionKind {
fn appl_sugg(&self, parent_unwrap_call: Option<Span>, primary_span: Span) -> (Applicability, Vec<(Span, String)>) {
let Some(unwrap_span) = parent_unwrap_call else {
return (Applicability::Unspecified, self.default_sugg(primary_span));
};

match &self {
FunctionKind::TryFromFunction(None) | FunctionKind::TryIntoFunction(None) => {
(Applicability::Unspecified, self.default_sugg(primary_span))
},
_ => (
Applicability::MachineApplicable,
self.machine_applicable_sugg(primary_span, unwrap_span),
),
}
}

fn default_sugg(&self, primary_span: Span) -> Vec<(Span, String)> {
let replacement = match *self {
FunctionKind::TryFromFunction(_) => "From::from",
FunctionKind::TryIntoFunction(_) => "Into::into",
FunctionKind::TryIntoMethod => "into",
};

vec![(primary_span, String::from(replacement))]
}

fn machine_applicable_sugg(&self, primary_span: Span, unwrap_span: Span) -> Vec<(Span, String)> {
let (trait_name, fn_name) = match self {
FunctionKind::TryFromFunction(_) => ("From".to_owned(), "from".to_owned()),
FunctionKind::TryIntoFunction(_) | FunctionKind::TryIntoMethod => ("Into".to_owned(), "into".to_owned()),
};

let mut sugg = match *self {
FunctionKind::TryFromFunction(Some(spans)) | FunctionKind::TryIntoFunction(Some(spans)) => match spans {
SpansKind::TraitFn { trait_span, fn_span } => vec![(trait_span, trait_name), (fn_span, fn_name)],
SpansKind::Fn { fn_span } => vec![(fn_span, fn_name)],
},
FunctionKind::TryIntoMethod => vec![(primary_span, fn_name)],
// Or the suggestion is not machine-applicable
_ => unreachable!(),
};

sugg.push((unwrap_span, String::new()));
sugg
}
}

fn check<'tcx>(
Expand All @@ -35,8 +89,8 @@ fn check<'tcx>(
&& self_ty != other_ty
&& let Some(self_ty) = self_ty.as_type()
&& let Some(from_into_trait) = cx.tcx.get_diagnostic_item(match kind {
FunctionKind::TryFromFunction => sym::From,
FunctionKind::TryIntoMethod | FunctionKind::TryIntoFunction => sym::Into,
FunctionKind::TryFromFunction(_) => sym::From,
FunctionKind::TryIntoMethod | FunctionKind::TryIntoFunction(_) => sym::Into,
})
// If `T: TryFrom<U>` and `T: From<U>` both exist, then that means that the `TryFrom`
// _must_ be from the blanket impl and cannot have been manually implemented
Expand All @@ -45,49 +99,37 @@ fn check<'tcx>(
&& implements_trait(cx, self_ty, from_into_trait, &[other_ty])
&& let Some(other_ty) = other_ty.as_type()
{
// Extend the span to include the unwrap/expect call:
// `foo.try_into().expect("..")`
// ^^^^^^^^^^^^^^^^^^^^^^^
//
// `try_into().unwrap()` specifically can be trivially replaced with just `into()`,
// so that can be machine-applicable
let parent_unwrap_call = get_parent_expr(cx, expr).and_then(|parent| {
if let ExprKind::MethodCall(path, .., span) = parent.kind
&& let sym::unwrap | sym::expect = path.ident.name
{
Some(span)
// include `.` before `unwrap`/`expect`
Some(span.with_lo(expr.span.hi()))
} else {
None
}
});
let (source_ty, target_ty, sugg, span, applicability) = match kind {
FunctionKind::TryIntoMethod if let Some(unwrap_span) = parent_unwrap_call => {
// Extend the span to include the unwrap/expect call:
// `foo.try_into().expect("..")`
// ^^^^^^^^^^^^^^^^^^^^^^^
//
// `try_into().unwrap()` specifically can be trivially replaced with just `into()`,
// so that can be machine-applicable

(
self_ty,
other_ty,
"into()",
primary_span.with_hi(unwrap_span.hi()),
Applicability::MachineApplicable,
)
},
FunctionKind::TryFromFunction => (
other_ty,
self_ty,
"From::from",
primary_span,
Applicability::Unspecified,
),
FunctionKind::TryIntoFunction => (
self_ty,
other_ty,
"Into::into",
primary_span,
Applicability::Unspecified,
),
FunctionKind::TryIntoMethod => (self_ty, other_ty, "into", primary_span, Applicability::Unspecified),

// If there is an unwrap/expect call, extend the span to include the call
let span = if let Some(unwrap_call) = parent_unwrap_call {
primary_span.with_hi(unwrap_call.hi())
} else {
primary_span
};

let (source_ty, target_ty) = match kind {
FunctionKind::TryIntoMethod | FunctionKind::TryIntoFunction(_) => (self_ty, other_ty),
FunctionKind::TryFromFunction(_) => (other_ty, self_ty),
};

let (applicability, sugg) = kind.appl_sugg(parent_unwrap_call, primary_span);

span_lint_and_then(
cx,
UNNECESSARY_FALLIBLE_CONVERSIONS,
Expand All @@ -97,7 +139,7 @@ fn check<'tcx>(
with_forced_trimmed_paths!({
diag.note(format!("converting `{source_ty}` to `{target_ty}` cannot fail"));
});
diag.span_suggestion(span, "use", sugg, applicability);
diag.multipart_suggestion("use", sugg, applicability);
},
);
}
Expand Down Expand Up @@ -125,13 +167,30 @@ pub(super) fn check_function(cx: &LateContext<'_>, expr: &Expr<'_>, callee: &Exp
&& let Some(item_def_id) = cx.qpath_res(qpath, callee.hir_id).opt_def_id()
&& let Some(trait_def_id) = cx.tcx.trait_of_item(item_def_id)
{
let qpath_spans = match qpath {
QPath::Resolved(_, path) => {
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(SpansKind::Fn {
fn_span: seg.ident.span,
}),
QPath::LangItem(_, _) => unreachable!("`TryFrom` and `TryInto` are not lang items"),
};

check(
cx,
expr,
cx.typeck_results().node_args(callee.hir_id),
match cx.tcx.get_diagnostic_name(trait_def_id) {
Some(sym::TryFrom) => FunctionKind::TryFromFunction,
Some(sym::TryInto) => FunctionKind::TryIntoFunction,
Some(sym::TryFrom) => FunctionKind::TryFromFunction(qpath_spans),
Some(sym::TryInto) => FunctionKind::TryIntoFunction(qpath_spans),
_ => return,
},
callee.span,
Expand Down
37 changes: 37 additions & 0 deletions tests/ui/unnecessary_fallible_conversions.fixed
View file
@@ -1,6 +1,43 @@
#![warn(clippy::unnecessary_fallible_conversions)]

fn main() {
// --- TryFromMethod `T::try_from(u)` ---

let _: i64 = 0i32.into();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = 0i32.into();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryFromFunction `T::try_from(U)` ---

let _ = i64::from(0i32);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _ = i64::from(0i32);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryIntoFunction `U::try_into(t)` ---

let _: i64 = i32::into(0);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = i32::into(0i32);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryFromFunction `<T as TryFrom<U>>::try_from(U)` ---

let _ = <i64 as From<i32>>::from(0);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _ = <i64 as From<i32>>::from(0);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryIntoFunction `<U as TryInto<_>>::try_into(U)` ---

let _: i64 = <i32 as Into<_>>::into(0);
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = <i32 as Into<_>>::into(0);
//~^ ERROR: use of a fallible conversion when an infallible one could be used
}
37 changes: 37 additions & 0 deletions tests/ui/unnecessary_fallible_conversions.rs
View file
@@ -1,6 +1,43 @@
#![warn(clippy::unnecessary_fallible_conversions)]

fn main() {
// --- TryFromMethod `T::try_from(u)` ---

let _: i64 = 0i32.try_into().unwrap();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = 0i32.try_into().expect("can't happen");
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryFromFunction `T::try_from(U)` ---

let _ = i64::try_from(0i32).unwrap();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _ = i64::try_from(0i32).expect("can't happen");
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryIntoFunction `U::try_into(t)` ---

let _: i64 = i32::try_into(0).unwrap();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = i32::try_into(0i32).expect("can't happen");
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryFromFunction `<T as TryFrom<U>>::try_from(U)` ---

let _ = <i64 as TryFrom<i32>>::try_from(0).unwrap();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _ = <i64 as TryFrom<i32>>::try_from(0).expect("can't happen");
//~^ ERROR: use of a fallible conversion when an infallible one could be used

// --- TryIntoFunction `<U as TryInto<_>>::try_into(U)` ---

let _: i64 = <i32 as TryInto<_>>::try_into(0).unwrap();
//~^ ERROR: use of a fallible conversion when an infallible one could be used

let _: i64 = <i32 as TryInto<_>>::try_into(0).expect("can't happen");
//~^ ERROR: use of a fallible conversion when an infallible one could be used
}

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