fix doc comments, use optional snippets

Author: Jacherr

clippy_lints/src/doc/doc_comment_double_space_linebreak.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::source::snippet;
+use clippy_utils::source::snippet_opt;
 use rustc_errors::Applicability;
 use rustc_lint::LateContext;
 use rustc_span::Span;
@@ -30,7 +30,8 @@ fn collect_doc_replacements(cx: &LateContext<'_>, spans: &[Span]) -> Vec<(Span,
     spans
         .iter()
         .map(|span| {
-            let s = snippet(cx, *span, "..");
+            // we already made sure the snippet exists when collecting spans
+            let s = snippet_opt(cx, *span).expect("snippet was already validated to exist");
             let after_newline = s.trim_start_matches(' ');
 
             let new_comment = format!("\\{after_newline}");

clippy_lints/src/doc/mod.rs

@@ -7,7 +7,7 @@ use clippy_config::Conf;
 use clippy_utils::attrs::is_doc_hidden;
 use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_then};
 use clippy_utils::macros::{is_panic, root_macro_call_first_node};
-use clippy_utils::source::snippet;
+use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::visitors::Visitable;
 use clippy_utils::{is_entrypoint_fn, is_trait_impl_item, method_chain_args};
@@ -626,11 +626,11 @@ declare_clippy_lint! {
 }
 
 declare_clippy_lint! {
-    /// Detects doc comment linebreaks that use double spaces to separate lines, instead of back-slash (\).
+    /// Detects doc comment linebreaks that use double spaces to separate lines, instead of back-slash (`\`).
     ///
     /// ### Why is this bad?
     /// Double spaces, when used as doc comment linebreaks, can be difficult to see, and may
-    /// accidentally be removed during automatic formatting or manual refactoring. The use of a back-slash (\)
+    /// accidentally be removed during automatic formatting or manual refactoring. The use of a back-slash (`\`)
     /// is clearer in this regard.
     ///
     /// ### Example
@@ -909,6 +909,7 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
     let mut code_level = 0;
     let mut blockquote_level = 0;
     let mut collected_breaks: Vec<Span> = Vec::new();
+    let mut is_first_paragraph = true;
 
     let mut containers = Vec::new();
 
@@ -1085,7 +1086,7 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
 
                 if let Some(span) = fragments.span(cx, range.clone())
                     && !span.from_expansion()
-                    && let snippet = snippet(cx, span, "..") 
+                    && let Some(snippet) = snippet_opt(cx, span)
                     && !snippet.trim().starts_with('\\')
                     && event == HardBreak {
                     collected_breaks.push(span);