Don't warn about invalid HTML tags in code blocks

src/librustdoc/passes/html_tags.rs

@@ -4,7 +4,7 @@ use crate::core::DocContext;
 use crate::fold::DocFolder;
 use crate::html::markdown::opts;
 use core::ops::Range;
-use pulldown_cmark::{Event, Parser};
+use pulldown_cmark::{Event, Parser, Tag};
 use rustc_session::lint;
 use std::iter::Peekable;
 use std::str::CharIndices;
@@ -196,14 +196,17 @@ impl<'a, 'tcx> DocFolder for InvalidHtmlTagsLinter<'a, 'tcx> {
 
             let mut tags = Vec::new();
             let mut is_in_comment = None;
+            let mut in_code_block = false;
 
             let p = Parser::new_ext(&dox, opts()).into_offset_iter();
 
             for (event, range) in p {
                 match event {
-                    Event::Html(text) | Event::Text(text) => {
+                    Event::Start(Tag::CodeBlock(_)) => in_code_block = true,
+                    Event::Html(text) | Event::Text(text) if !in_code_block => {
                         extract_tags(&mut tags, &text, range, &mut is_in_comment, &report_diag)
                     }
+                    Event::End(Tag::CodeBlock(_)) => in_code_block = false,
                     _ => {}
                 }
             }