1 files changed, 44 insertions, 45 deletions
diff --git a/src/tools/clippy/clippy_lints/src/regex.rs b/src/tools/clippy/clippy_lints/src/regex.rs
index 1fda58fa5..9e6c6c73d 100644
--- a/src/tools/clippy/clippy_lints/src/regex.rs
+++ b/src/tools/clippy/clippy_lints/src/regex.rs
@@ -1,5 +1,8 @@
+use std::fmt::Display;
+
 use clippy_utils::consts::{constant, Constant};
 use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
+use clippy_utils::source::snippet_opt;
 use clippy_utils::{match_def_path, paths};
 use if_chain::if_chain;
 use rustc_ast::ast::{LitKind, StrStyle};
@@ -77,13 +80,45 @@ impl<'tcx> LateLintPass<'tcx> for Regex {
     }
 }
 
-#[must_use]
-fn str_span(base: Span, c: regex_syntax::ast::Span, offset: u8) -> Span {
-    let offset = u32::from(offset);
-    let end = base.lo() + BytePos(u32::try_from(c.end.offset).expect("offset too large") + offset);
-    let start = base.lo() + BytePos(u32::try_from(c.start.offset).expect("offset too large") + offset);
-    assert!(start <= end);
-    Span::new(start, end, base.ctxt(), base.parent())
+fn lint_syntax_error(cx: &LateContext<'_>, error: &regex_syntax::Error, unescaped: &str, base: Span, offset: u8) {
+    let parts: Option<(_, _, &dyn Display)> = match &error {
+        regex_syntax::Error::Parse(e) => Some((e.span(), e.auxiliary_span(), e.kind())),
+        regex_syntax::Error::Translate(e) => Some((e.span(), None, e.kind())),
+        _ => None,
+    };
+
+    let convert_span = |regex_span: &regex_syntax::ast::Span| {
+        let offset = u32::from(offset);
+        let start = base.lo() + BytePos(u32::try_from(regex_span.start.offset).expect("offset too large") + offset);
+        let end = base.lo() + BytePos(u32::try_from(regex_span.end.offset).expect("offset too large") + offset);
+
+        Span::new(start, end, base.ctxt(), base.parent())
+    };
+
+    if let Some((primary, auxiliary, kind)) = parts
+        && let Some(literal_snippet) = snippet_opt(cx, base)
+        && let Some(inner) = literal_snippet.get(offset as usize..)
+        // Only convert to native rustc spans if the parsed regex matches the
+        // source snippet exactly, to ensure the span offsets are correct
+        && inner.get(..unescaped.len()) == Some(unescaped)
+    {
+        let spans = if let Some(auxiliary) = auxiliary {
+            vec![convert_span(primary), convert_span(auxiliary)]
+        } else {
+            vec![convert_span(primary)]
+        };
+
+        span_lint(cx, INVALID_REGEX, spans, &format!("regex syntax error: {kind}"));
+    } else {
+        span_lint_and_help(
+            cx,
+            INVALID_REGEX,
+            base,
+            &error.to_string(),
+            None,
+            "consider using a raw string literal: `r\"..\"`",
+        );
+    }
 }
 
 fn const_str<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<String> {
@@ -155,25 +190,7 @@ fn check_regex<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) {
                         span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl);
                     }
                 },
-                Err(regex_syntax::Error::Parse(e)) => {
-                    span_lint(
-                        cx,
-                        INVALID_REGEX,
-                        str_span(expr.span, *e.span(), offset),
-                        &format!("regex syntax error: {}", e.kind()),
-                    );
-                },
-                Err(regex_syntax::Error::Translate(e)) => {
-                    span_lint(
-                        cx,
-                        INVALID_REGEX,
-                        str_span(expr.span, *e.span(), offset),
-                        &format!("regex syntax error: {}", e.kind()),
-                    );
-                },
-                Err(e) => {
-                    span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {e}"));
-                },
+                Err(e) => lint_syntax_error(cx, &e, r, expr.span, offset),
             }
         }
     } else if let Some(r) = const_str(cx, expr) {
@@ -183,25 +200,7 @@ fn check_regex<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) {
                     span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl);
                 }
             },
-            Err(regex_syntax::Error::Parse(e)) => {
-                span_lint(
-                    cx,
-                    INVALID_REGEX,
-                    expr.span,
-                    &format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()),
-                );
-            },
-            Err(regex_syntax::Error::Translate(e)) => {
-                span_lint(
-                    cx,
-                    INVALID_REGEX,
-                    expr.span,
-                    &format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()),
-                );
-            },
-            Err(e) => {
-                span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {e}"));
-            },
+            Err(e) => span_lint(cx, INVALID_REGEX, expr.span, &e.to_string()),
         }
     }
 }