Code Block should not render embeds (or shortcodes)

packages/block-library/src/code/edit.js

@@ -7,13 +7,14 @@ import { __ } from '@wordpress/i18n';
  * Internal dependencies
  */
 import { PlainText } from '@wordpress/block-editor';
+import { escape, unescape } from './utils';
 
 export default function CodeEdit( { attributes, setAttributes, className } ) {
 	return (
 		<div className={ className }>
 			<PlainText
-				value={ attributes.content }
-				onChange={ ( content ) => setAttributes( { content } ) }
+				value={ unescape( attributes.content ) }
+				onChange={ ( content ) => setAttributes( { content: escape( content ) } ) }
 				placeholder={ __( 'Write code…' ) }
 				aria-label={ __( 'Code' ) }
 			/>

packages/block-library/src/code/edit.native.js

@@ -12,6 +12,7 @@ import { __ } from '@wordpress/i18n';
  * Internal dependencies
  */
 import { PlainText } from '@wordpress/block-editor';
+import { escape, unescape } from './utils';
 
 /**
  * Block code style
@@ -26,11 +27,11 @@ export default function CodeEdit( props ) {
 	return (
 		<View>
 			<PlainText
-				value={ attributes.content }
+				value={ unescape( attributes.content ) }
 				style={ [ style, styles.blockCode ] }
 				multiline={ true }
 				underlineColorAndroid="transparent"
-				onChange={ ( content ) => setAttributes( { content } ) }
+				onChange={ ( content ) => setAttributes( { content: escape( content ) } ) }
 				placeholder={ __( 'Write code…' ) }
 				aria-label={ __( 'Code' ) }
 				isSelected={ props.isSelected }

packages/block-library/src/code/utils.js

@@ -0,0 +1,117 @@
+/**
+ * External dependencies
+ */
+import { flow } from 'lodash';
+
+/**
+ * Escapes ampersands, shortcodes, and links.
+ *
+ * @param {string} content The content of a code block.
+ * @return {string} The given content with some characters escaped.
+ */
+export function escape( content ) {
+	return flow(
+		escapeAmpersands,
+		escapeOpeningSquareBrackets,
+		escapeProtocolInIsolatedUrls
+	)( content || '' );
+}
+
+/**
+ * Unescapes escaped ampersands, shortcodes, and links.
+ *
+ * @param {string} content Content with (maybe) escaped ampersands, shortcodes, and links.
+ * @return {string} The given content with escaped characters unescaped.
+ */
+export function unescape( content ) {
+	return flow(
+		unescapeProtocolInIsolatedUrls,
+		unescapeOpeningSquareBrackets,
+		unescapeAmpersands
+	)( content || '' );
+}
+
+/**
+ * Returns the given content with all its ampersand characters converted
+ * into their HTML entity counterpart (i.e. & => &)
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with its ampersands converted into
+ *                  their HTML entity counterpart (i.e. & => &)
+ */
+function escapeAmpersands( content ) {
+	return content.replace( /&/g, '&' );
+}
+
+/**
+ * Returns the given content with all & HTML entities converted into &.
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with all & HTML entities
+ *                  converted into &.
+ */
+function unescapeAmpersands( content ) {
+	return content.replace( /&/g, '&' );
+}
+
+/**
+ * Returns the given content with all opening shortcode characters converted
+ * into their HTML entity counterpart (i.e. [ => [). For instance, a
+ * shortcode like [embed] becomes [embed]
+ *
+ * This function replicates the escaping of HTML tags, where a tag like
+ * <strong> becomes &lt;strong>.
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with its opening shortcode characters
+ *                  converted into their HTML entity counterpart
+ *                  (i.e. [ => &#91;)
+ */
+function escapeOpeningSquareBrackets( content ) {
+	return content.replace( /\[/g, '&#91;' );
+}
+
+/**
+ * Returns the given content translating all &#91; into [.
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with all &#91; into [.
+ */
+function unescapeOpeningSquareBrackets( content ) {
+	return content.replace( /&#91;/g, '[' );
+}
+
+/**
+ * Converts the first two forward slashes of any isolated URL into their HTML
+ * counterparts (i.e. // => &#47;&#47;). For instance, https://youtube.com/watch?x
+ * becomes https:&#47;&#47;youtube.com/watch?x.
+ *
+ * An isolated URL is a URL that sits in its own line, surrounded only by spacing
+ * characters.
+ *
+ * See https://github.com/WordPress/wordpress-develop/blob/5.1.1/src/wp-includes/class-wp-embed.php#L403
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with its ampersands converted into
+ *                  their HTML entity counterpart (i.e. & => &amp;)
+ */
+function escapeProtocolInIsolatedUrls( content ) {
+	return content.replace( /^(\s*https?:)\/\/([^\s<>"]+\s*)$/m, '$1&#47;&#47;$2' );
+}
+
+/**
+ * Converts the first two forward slashes of any isolated URL from the HTML entity
+ * &#73; into /.
+ *
+ * An isolated URL is a URL that sits in its own line, surrounded only by spacing
+ * characters.
+ *
+ * See https://github.com/WordPress/wordpress-develop/blob/5.1.1/src/wp-includes/class-wp-embed.php#L403
+ *
+ * @param {string}  content The content of a code block.
+ * @return {string} The given content with the first two forward slashes of any
+ *                  isolated URL from the HTML entity &#73; into /.
+ */
+function unescapeProtocolInIsolatedUrls( content ) {
+	return content.replace( /^(\s*https?:)&#47;&#47;([^\s<>"]+\s*)$/m, '$//$2' );
+}