diff --git src/wp-admin/includes/post.php src/wp-admin/includes/post.php
index 9356ace..7b1b5f0 100644
--- src/wp-admin/includes/post.php
+++ src/wp-admin/includes/post.php
@@ -1234,6 +1234,24 @@ function get_sample_permalink($id, $title = null, $name = null) {
 		$permalink = str_replace('%pagename%', "{$uri}%pagename%", $permalink);
 	}
 
+	// If the name is numeric and non-zero, verify that it won't clash with date archive URLs.
+	if ( preg_match( '/^[0-9]+$/', $post->post_name ) && $post_name_num = intval( $post->post_name ) ) {
+		$permastructs   = array_values( array_filter( explode( '/', get_option( 'permalink_structure' ) ) ) );
+		$postname_index = array_search( '%postname%', $permastructs );
+
+		/*
+		 * Find potential date conflicts. Any integer in the first permastruct position could be a year.
+		 * An integer between 1 and 12 that follows 'year' conflicts with 'monthnum'. An integer between 1 and
+		 * 31 that follows 'monthnum' conflicts with 'day'.
+		 */
+		if ( 0 === $postname_index ||
+		     ( '%year%' === $permastructs[ $postname_index - 1 ] && 13 > $post_name_num ) ||
+		     ( '%monthnum%' === $permastructs[ $postname_index - 1 ] && 32 > $post_name_num )
+		   ) {
+			$post->post_name = wp_unique_post_slug( $post->post_name, 0, $post->post_status, $post->post_type, $post->post_parent );
+		}
+	}
+
 	/** This filter is documented in wp-admin/edit-tag-form.php */
 	$permalink = array( $permalink, apply_filters( 'editable_slug', $post->post_name ) );
 	$post->post_status = $original_status;
diff --git src/wp-includes/class-wp.php src/wp-includes/class-wp.php
index a079c12..5bb6883 100644
--- src/wp-includes/class-wp.php
+++ src/wp-includes/class-wp.php
@@ -306,6 +306,9 @@ class WP {
 			}
 		}
 
+		// Resolve conflicts between posts with numeric slugs and date archive queries.
+		$this->query_vars = _resolve_numeric_slug_conflicts( $this->query_vars );
+
 		foreach ( (array) $this->private_query_vars as $var) {
 			if ( isset($this->extra_query_vars[$var]) )
 				$this->query_vars[$var] = $this->extra_query_vars[$var];
diff --git src/wp-includes/rewrite.php src/wp-includes/rewrite.php
index 45d28ce..eb3f52a 100644
--- src/wp-includes/rewrite.php
+++ src/wp-includes/rewrite.php
@@ -275,6 +275,99 @@ function _wp_filter_taxonomy_base( $base ) {
 }
 
 /**
+ * Resolve numeric slugs that collide with date permalinks.
+ *
+ * Permalinks of posts with numeric slugs can sometimes look to `WP_Query::parse_query()` like a date archive,
+ * as when your permalink structure is `/%year%/%postname%/` and a post with post_name '05' has the URL
+ * `/2015/05/`. This function detects these conflicts and resolves conflicts in favor of the post permalink.
+ *
+ * @since 4.2.0
+ * @access private
+ *
+ * @param array $query_vars Query variables for setting up the WordPress Query Loop.
+ * @return array
+ */
+function _resolve_numeric_slug_conflicts( $query_vars = array() ) {
+	if ( ! isset( $query_vars['year'] ) && ! isset( $query_vars['monthnum'] ) && ! isset( $query_vars['day'] ) ) {
+		return $query_vars;
+	}
+
+	// Identify the 'postname' position in the permastruct array.
+	$permastructs   = array_values( array_filter( explode( '/', get_option( 'permalink_structure' ) ) ) );
+	$postname_index = array_search( '%postname%', $permastructs );
+
+	if ( false === $postname_index ) {
+		return $query_vars;
+	}
+
+	/*
+	 * A numeric slug could be confused with a year, month, or day, depending on position. To account for
+	 * the possibility of post pagination (eg 2015/2 for the second page of a post called '2015'), our
+	 * `is_*` checks are generous: check for year-slug clashes when `is_year` *or* `is_month`, and check
+	 * for month-slug clashes when `is_month` *or* `is_day`.
+	 */
+	$compare = '';
+	if ( 0 === $postname_index && ( isset( $query_vars['year'] ) || isset( $query_vars['monthnum'] ) ) ) {
+		$compare = 'year';
+	} else if ( '%year%' === $permastructs[ $postname_index - 1 ] && ( isset( $query_vars['monthnum'] ) || isset( $query_vars['day'] ) ) ) {
+		$compare = 'monthnum';
+	} else if ( '%monthnum%' === $permastructs[ $postname_index - 1 ] && isset( $query_vars['day'] ) ) {
+		$compare = 'day';
+	}
+
+	if ( ! $compare ) {
+		return $query_vars;
+	}
+
+	// This is the potentially clashing slug.
+	$value = $query_vars[ $compare ];
+
+	$post = get_page_by_path( $value, OBJECT, 'post' );
+	if ( ! ( $post instanceof WP_Post ) ) {
+		return $query_vars;
+	}
+
+	/*
+	 * If the located post contains nextpage pagination, then the URL chunk following postname may be
+	 * intended as the page number. Verify that it's a valid page before resolving to it.
+	 */
+	$maybe_page = '';
+	if ( 'year' === $compare && isset( $query_vars['monthnum'] ) ) {
+		$maybe_page = $query_vars['monthnum'];
+	} else if ( 'monthnum' === $compare && isset( $query_vars['day'] ) ) {
+		$maybe_page = $query_vars['day'];
+	}
+
+	$post_page_count = substr_count( $post->post_content, '<!--nextpage-->' ) + 1;
+
+	// If the post doesn't have multiple pages, but a 'page' candidate is found, resolve to the date archive.
+	if ( 1 === $post_page_count && $maybe_page ) {
+		return $query_vars;
+	}
+
+	// If the post has multiple pages and the 'page' number isn't valid, resolve to the date archive.
+	if ( $post_page_count > 1 && $maybe_page > $post_page_count ) {
+		return $query_vars;
+	}
+
+	// If we've gotten to this point, we have a slug/date clash. First, adjust for nextpage.
+	if ( '' !== $maybe_page ) {
+		$query_vars['page'] = intval( $maybe_page );
+	}
+
+	// Next, unset autodetected date-related query vars.
+	unset( $query_vars['year'] );
+	unset( $query_vars['monthnum'] );
+	unset( $query_vars['day'] );
+
+	// Then, set the identified post.
+	$query_vars['name'] = $post->post_name;
+
+	// Finally, return the modified query vars.
+	return $query_vars;
+}
+
+/**
  * Examine a url and try to determine the post ID it represents.
  *
  * Checks are supposedly from the hosted site blog.
@@ -389,6 +482,9 @@ function url_to_postid($url) {
 				}
 			}
 
+			// Resolve conflicts between posts with numeric slugs and date archive queries.
+			$query = _resolve_numeric_slug_conflicts( $query );
+
 			// Do the query
 			$query = new WP_Query( $query );
 			if ( ! empty( $query->posts ) && $query->is_singular )
diff --git tests/phpunit/tests/admin/includesPost.php tests/phpunit/tests/admin/includesPost.php
index 5d2623a..e25a917 100644
--- tests/phpunit/tests/admin/includesPost.php
+++ tests/phpunit/tests/admin/includesPost.php
@@ -313,4 +313,168 @@ class Tests_Admin_includesPost extends WP_UnitTestCase {
 		$wp_rewrite->set_permalink_structure( $old_permalink_structure );
 		flush_rewrite_rules();
 	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_avoid_slugs_that_would_create_clashes_with_year_archives() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '2015',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '2015-2', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_allow_yearlike_slugs_if_permastruct_does_not_cause_an_archive_conflict() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '2015',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '2015', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_avoid_slugs_that_would_create_clashes_with_month_archives() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '11',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '11-2', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_ignore_potential_month_conflicts_for_invalid_monthnum() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '13',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '13', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_avoid_slugs_that_would_create_clashes_with_day_archives() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '30',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '30-2', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_iterate_slug_suffix_when_a_date_conflict_is_found() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$this->factory->post->create( array(
+			'post_name' => '30-2',
+		) );
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '30',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '30-3', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_ignore_potential_day_conflicts_for_invalid_day() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '32',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '32', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
+
+	/**
+	 * @ticket 5305
+	 */
+	public function test_get_sample_permalink_should_allow_daylike_slugs_if_permastruct_does_not_cause_an_archive_conflict() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%month%/%day%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$p = $this->factory->post->create( array(
+			'post_name' => '30',
+		) );
+
+		$found = get_sample_permalink( $p );
+		$this->assertEquals( '30', $found[1] );
+
+		$wp_rewrite->set_permalink_structure( '' );
+		flush_rewrite_rules();
+	}
 }
diff --git tests/phpunit/tests/rewrite/numericSlugs.php tests/phpunit/tests/rewrite/numericSlugs.php
new file mode 100644
index 0000000..52d8ca7
--- /dev/null
+++ tests/phpunit/tests/rewrite/numericSlugs.php
@@ -0,0 +1,465 @@
+<?php
+
+/**
+ * @group rewrite
+ * @ticket 5305
+ */
+class Tests_Rewrite_NumericSlugs extends WP_UnitTestCase {
+	private $old_current_user;
+
+	public function setUp() {
+		parent::setUp();
+		$this->author_id = $this->factory->user->create( array( 'role' => 'editor' ) );
+	}
+
+	public function test_go_to_year_segment_collision_without_title() {
+		global $wp_rewrite, $wpdb;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '2015',
+			'post_date'    => '2015-02-01 01:00:00'
+		) );
+
+		// Force an ID that resembles a year format
+		$wpdb->update(
+			$wpdb->posts,
+			array(
+				'ID'   => '2015',
+				'guid' => 'http://example.org/?p=2015'
+			),
+			array( 'ID' => $id )
+		);
+
+		$this->go_to( get_permalink( '2015' ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_year_segment_collision_without_title() {
+		global $wp_rewrite, $wpdb;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '2015',
+			'post_date'    => '2015-02-01 01:00:00'
+		) );
+
+		// Force an ID that resembles a year format
+		$wpdb->update(
+			$wpdb->posts,
+			array(
+				'ID'   => '2015',
+				'guid' => 'http://example.org/?p=2015'
+			),
+			array( 'ID' => $id )
+		);
+
+		$this->assertEquals( '2015', url_to_postid( get_permalink( '2015' ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_year_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '2015',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_year_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '2015',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_month_segment_collision_without_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '02',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_month_segment_collision_without_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '02',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_month_segment_collision_without_title_no_leading_zero() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '2',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_month_segment_collision_without_title_no_leading_zero() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '2',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_month_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '02',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_month_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '02',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_month_segment_collision_with_title_no_leading_zero() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '2',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_month_segment_collision_with_title_no_leading_zero() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '2',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_day_segment_collision_without_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '01',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_day_segment_collision_without_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '',
+			'post_name'    => '01',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_go_to_day_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '01',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_url_to_postid_day_segment_collision_with_title() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '01',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->assertEquals( $id, url_to_postid( get_permalink( $id ) ) );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_numeric_slug_permalink_conflicts_should_only_be_resolved_for_the_main_query() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => rand_str(),
+			'post_title'   => '01',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$q = new WP_Query( array(
+			'year'     => '2015',
+			'monthnum' => '02',
+			'day'      => '01',
+		) );
+
+		$this->assertTrue( $q->is_day );
+		$this->assertFalse( $q->is_single );
+
+		$wp_rewrite->set_permalink_structure('');
+	}
+
+	public function test_date_slug_collision_should_distinguish_valid_pagination_from_date() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => 'Page 0<!--nextpage-->Page 1<!--nextpage-->Page 2<!--nextpage-->Page 3',
+			'post_title'   => '02',
+			'post_date'    => '2015-02-01 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) . '1' );
+
+		$this->assertFalse( is_day() );
+	}
+
+	public function test_date_slug_collision_should_distinguish_too_high_pagination_from_date() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => 'Page 0<!--nextpage-->Page 1<!--nextpage-->Page 2<!--nextpage-->Page 3',
+			'post_title'   => '02',
+			'post_date'    => '2015-02-05 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) . '5' );
+
+		$this->assertTrue( is_day() );
+	}
+
+	public function test_date_slug_collision_should_not_require_pagination_query_var() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => 'Page 0<!--nextpage-->Page 1<!--nextpage-->Page 2<!--nextpage-->Page 3',
+			'post_title'   => '02',
+			'post_date'    => '2015-02-05 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) );
+
+		$this->assertQueryTrue( 'is_single', 'is_singular' );
+		$this->assertFalse( is_date() );
+	}
+
+	public function test_date_slug_collision_should_be_ignored_when_pagination_var_is_present_but_post_does_not_have_multiple_pages() {
+		global $wp_rewrite;
+		$wp_rewrite->init();
+		$wp_rewrite->set_permalink_structure( '/%year%/%postname%/' );
+		$wp_rewrite->flush_rules();
+
+		$id = $this->factory->post->create( array(
+			'post_author'  => $this->author_id,
+			'post_status'  => 'publish',
+			'post_content' => 'This post does not have pagination.',
+			'post_title'   => '02',
+			'post_date'    => '2015-02-05 01:00:00',
+		) );
+
+		$this->go_to( get_permalink( $id ) . '5' );
+
+		$this->assertTrue( is_day() );
+	}
+}