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lint: port no-op method call diagnostics

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Signed-off-by: David Wood <david.wood@huawei.com>
This commit is contained in:
David Wood 2022-06-27 16:52:51 +01:00
parent 096a69dd19
commit 855f23773b
2 changed files with 11 additions and 12 deletions
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4
compiler/rustc_error_messages/locales/en-US/lint.ftl
View file

@ -124,3 +124,7 @@ lint-non-snake-case = {$sort} `{$name}` should have a snake case name
lint-non-upper_case-global = {$sort} `{$name}` should have an upper case name lint-non-upper_case-global = {$sort} `{$name}` should have an upper case name
.suggestion = convert the identifier to upper case .suggestion = convert the identifier to upper case
.label = should have an UPPER_CASE name .label = should have an UPPER_CASE name
lint-noop-method-call = call to `.{$method}()` on a reference in this situation does nothing
.label = unnecessary method call
.note = the type `{$receiver_ty}` which `{$method}` is being called on is the same as the type returned from `{$method}`, so the method call does not do anything and can be removed

19
compiler/rustc_lint/src/noop_method_call.rs
View file

@ -2,6 +2,7 @@ use crate::context::LintContext;
use crate::rustc_middle::ty::TypeFoldable; use crate::rustc_middle::ty::TypeFoldable;
use crate::LateContext; use crate::LateContext;
use crate::LateLintPass; use crate::LateLintPass;
use rustc_errors::fluent;
use rustc_hir::def::DefKind; use rustc_hir::def::DefKind;
use rustc_hir::{Expr, ExprKind}; use rustc_hir::{Expr, ExprKind};
use rustc_middle::ty; use rustc_middle::ty;
@ -80,7 +81,6 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
) { ) {
return; return;
} }
let method = &call.ident.name;
let receiver = &elements[0]; let receiver = &elements[0];
let receiver_ty = cx.typeck_results().expr_ty(receiver); let receiver_ty = cx.typeck_results().expr_ty(receiver);
let expr_ty = cx.typeck_results().expr_ty_adjusted(expr); let expr_ty = cx.typeck_results().expr_ty_adjusted(expr);
@ -90,19 +90,14 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
return; return;
} }
let expr_span = expr.span; let expr_span = expr.span;
let note = format!(
"the type `{:?}` which `{}` is being called on is the same as \
the type returned from `{}`, so the method call does not do \
anything and can be removed",
receiver_ty, method, method,
);
let span = expr_span.with_lo(receiver.span.hi()); let span = expr_span.with_lo(receiver.span.hi());
cx.struct_span_lint(NOOP_METHOD_CALL, span, |lint| { cx.struct_span_lint(NOOP_METHOD_CALL, span, |lint| {
let method = &call.ident.name; lint.build(fluent::lint::noop_method_call)
let message = .set_arg("method", call.ident.name)
format!("call to `.{}()` on a reference in this situation does nothing", &method,); .set_arg("receiver_ty", receiver_ty)
lint.build(&message).span_label(span, "unnecessary method call").note(&note).emit(); .span_label(span, fluent::lint::label)
.note(fluent::lint::note)
.emit();
}); });
} }
} }