Improve invalid UTF-8 lint by finding the expression initializer

1 files changed, 14 insertions, 11 deletions

diff --git a/compiler/rustc_lint/src/invalid_from_utf8.rs b/compiler/rustc_lint/src/invalid_from_utf8.rs
index 3291286ad67..1841e7c85a8 100644
--- a/compiler/rustc_lint/src/invalid_from_utf8.rs
+++ b/compiler/rustc_lint/src/invalid_from_utf8.rs
@@ -1,6 +1,6 @@
 use std::str::Utf8Error;
 
-use rustc_ast::{BorrowKind, LitKind};
+use rustc_ast::LitKind;
 use rustc_hir::{Expr, ExprKind};
 use rustc_span::source_map::Spanned;
 use rustc_span::sym;
@@ -11,7 +11,7 @@ use crate::{LateContext, LateLintPass, LintContext};
 declare_lint! {
     /// The `invalid_from_utf8_unchecked` lint checks for calls to
     /// `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut`
-    /// with an invalid UTF-8 literal.
+    /// with a known invalid UTF-8 value.
     ///
     /// ### Example
     ///
@@ -36,7 +36,7 @@ declare_lint! {
 declare_lint! {
     /// The `invalid_from_utf8` lint checks for calls to
     /// `std::str::from_utf8` and `std::str::from_utf8_mut`
-    /// with an invalid UTF-8 literal.
+    /// with a known invalid UTF-8 value.
     ///
     /// ### Example
     ///
@@ -67,8 +67,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidFromUtf8 {
             && [sym::str_from_utf8, sym::str_from_utf8_mut,
                 sym::str_from_utf8_unchecked, sym::str_from_utf8_unchecked_mut].contains(&diag_item)
         {
-            let lint = |utf8_error: Utf8Error| {
-                let label = arg.span;
+            let lint = |label, utf8_error: Utf8Error| {
                 let method = diag_item.as_str().strip_prefix("str_").unwrap();
                 let method = format!("std::str::{method}");
                 let valid_up_to = utf8_error.valid_up_to();
@@ -78,22 +77,26 @@ impl<'tcx> LateLintPass<'tcx> for InvalidFromUtf8 {
                     if is_unchecked_variant { INVALID_FROM_UTF8_UNCHECKED } else { INVALID_FROM_UTF8 },
                     expr.span,
                     if is_unchecked_variant {
-                        InvalidFromUtf8Diag::Unchecked { method,  valid_up_to, label }
+                        InvalidFromUtf8Diag::Unchecked { method, valid_up_to, label }
                     } else {
-                        InvalidFromUtf8Diag::Checked { method,  valid_up_to, label }
+                        InvalidFromUtf8Diag::Checked { method, valid_up_to, label }
                     }
                 )
             };
 
-            match &arg.kind {
+            let mut init = cx.expr_or_init(arg);
+            while let ExprKind::AddrOf(.., inner) = init.kind {
+                init = cx.expr_or_init(inner);
+            }
+            match init.kind {
                 ExprKind::Lit(Spanned { node: lit, .. }) => {
                     if let LitKind::ByteStr(bytes, _) = &lit
                         && let Err(utf8_error) = std::str::from_utf8(bytes)
                     {
-                        lint(utf8_error);
+                        lint(init.span, utf8_error);
                     }
                 },
-                ExprKind::AddrOf(BorrowKind::Ref, _, Expr { kind: ExprKind::Array(args), .. }) => {
+                ExprKind::Array(args) => {
                     let elements = args.iter().map(|e|{
                         match &e.kind {
                             ExprKind::Lit(Spanned { node: lit, .. }) => match lit {
@@ -108,7 +111,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidFromUtf8 {
                     if let Some(elements) = elements
                         && let Err(utf8_error) = std::str::from_utf8(&elements)
                     {
-                        lint(utf8_error);
+                        lint(init.span, utf8_error);
                     }
                 }
                 _ => {}