Parameterize peel_casts follow init behavior

Author: Urgau

compiler/rustc_lint/src/ptr_nulls.rs

@@ -5,7 +5,7 @@ use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::{Span, sym};
 
 use crate::lints::{InvalidNullArgumentsDiag, UselessPtrNullChecksDiag};
-use crate::utils::peel_casts;
+use crate::utils::{FollowInit, peel_casts};
 use crate::{LateContext, LateLintPass, LintContext};
 
 declare_lint! {
@@ -112,7 +112,7 @@ fn useless_check<'a, 'tcx: 'a>(
 
 /// Checks if the given expression is a null pointer (modulo casting)
 fn is_null_ptr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Span> {
-    let (expr, _) = peel_casts(cx, expr);
+    let (expr, _) = peel_casts(cx, FollowInit::Yes, expr);
 
     if let ExprKind::Call(path, []) = expr.kind
         && let ExprKind::Path(ref qpath) = path.kind

compiler/rustc_lint/src/reference_casting.rs

@@ -6,7 +6,7 @@ use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::sym;
 
 use crate::lints::InvalidReferenceCastingDiag;
-use crate::utils::peel_casts;
+use crate::utils::{FollowInit, peel_casts};
 use crate::{LateContext, LateLintPass, LintContext};
 
 declare_lint! {
@@ -48,7 +48,9 @@ impl<'tcx> LateLintPass<'tcx> for InvalidReferenceCasting {
             // small cache to avoid recomputing needlessly computing peel_casts of init
             let mut peel_casts = {
                 let mut peel_casts_cache = None;
-                move || *peel_casts_cache.get_or_insert_with(|| peel_casts(cx, init))
+                move || {
+                    *peel_casts_cache.get_or_insert_with(|| peel_casts(cx, FollowInit::Yes, init))
+                }
             };
 
             if matches!(pat, PatternKind::Borrow { mutbl: Mutability::Mut } | PatternKind::Assign)

compiler/rustc_lint/src/utils.rs

@@ -3,13 +3,20 @@ use rustc_span::sym;
 
 use crate::LateContext;
 
+#[derive(Clone, Copy, PartialEq)]
+pub(crate) enum FollowInit {
+    Yes,
+    No,
+}
+
 /// Given an expression, peel all of casts (`<expr> as ...`, `<expr>.cast{,_mut,_const}()`,
 /// `ptr::from_ref(<expr>)`, ...) and init expressions.
 ///
 /// Returns the innermost expression and a boolean representing if one of the casts was
 /// `UnsafeCell::raw_get(<expr>)`
 pub(crate) fn peel_casts<'tcx>(
     cx: &LateContext<'tcx>,
+    follow_init: FollowInit,
     mut e: &'tcx Expr<'tcx>,
 ) -> (&'tcx Expr<'tcx>, bool) {
     let mut gone_trough_unsafe_cell_raw_get = false;
@@ -41,13 +48,15 @@ pub(crate) fn peel_casts<'tcx>(
                 gone_trough_unsafe_cell_raw_get = true;
             }
             arg
-        } else {
+        } else if follow_init == FollowInit::Yes {
             let init = cx.expr_or_init(e);
             if init.hir_id != e.hir_id {
                 init
             } else {
                 break;
             }
+        } else {
+            break;
         };
     }