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Rollup merge of #134586 - Urgau:fn-ptr-lint-option, r=compiler-errors

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Also lint on option of function pointer comparisons

This PR is the first part of #134536, ie. the linting on `Option<{fn ptr}>` in the `unpredictable_function_pointer_comparisons` lint, which isn't part of the lang nomination that the second part is going trough, and so should be able to be approved independently.

Related to https://github.com/rust-lang/rust/issues/134527
r? `@compiler-errors`
This commit is contained in:
Matthias Krüger 2024-12-21 01:30:18 +01:00 • committed by GitHub
commit b7ac8d78c5
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3 changed files with 50 additions and 2 deletions
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22
compiler/rustc_lint/src/types.rs
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@ -4,7 +4,7 @@ use std::ops::ControlFlow;
use rustc_abi::{BackendRepr, ExternAbi, TagEncoding, Variants, WrappingRange};
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::DiagMessage;
use rustc_hir::{Expr, ExprKind};
use rustc_hir::{Expr, ExprKind, LangItem};
use rustc_middle::bug;
use rustc_middle::ty::layout::{LayoutOf, SizeSkeleton};
use rustc_middle::ty::{
@ -444,7 +444,25 @@ fn lint_fn_pointer<'tcx>(
let (l_ty, l_ty_refs) = peel_refs(l_ty);
let (r_ty, r_ty_refs) = peel_refs(r_ty);
if !l_ty.is_fn() || !r_ty.is_fn() {
if l_ty.is_fn() && r_ty.is_fn() {
// both operands are function pointers, fallthrough
} else if let ty::Adt(l_def, l_args) = l_ty.kind()
&& let ty::Adt(r_def, r_args) = r_ty.kind()
&& cx.tcx.is_lang_item(l_def.did(), LangItem::Option)
&& cx.tcx.is_lang_item(r_def.did(), LangItem::Option)
&& let Some(l_some_arg) = l_args.get(0)
&& let Some(r_some_arg) = r_args.get(0)
&& l_some_arg.expect_ty().is_fn()
&& r_some_arg.expect_ty().is_fn()
{
// both operands are `Option<{function ptr}>`
return cx.emit_span_lint(
UNPREDICTABLE_FUNCTION_POINTER_COMPARISONS,
e.span,
UnpredictableFunctionPointerComparisons::Warn,
);
} else {
// types are not function pointers, nothing to do
return;
}