diff --git a/bin/functionMetadata_original.php b/bin/functionMetadata_original.php
index 17be4631a9e..7a1f8930ab2 100644
--- a/bin/functionMetadata_original.php
+++ b/bin/functionMetadata_original.php
@@ -94,6 +94,118 @@
 	'link' => ['hasSideEffects' => true],
 	'mkdir' => ['hasSideEffects' => true],
 	'move_uploaded_file' => ['hasSideEffects' => true],
+	'mysqli_affected_rows' => ['hasSideEffects' => true],
+	'mysqli_autocommit' => ['hasSideEffects' => true],
+	'mysqli_begin_transaction' => ['hasSideEffects' => true],
+	'mysqli_bind_param' => ['hasSideEffects' => true],
+	'mysqli_bind_result' => ['hasSideEffects' => true],
+	'mysqli_change_user' => ['hasSideEffects' => true],
+	'mysqli_character_set_name' => ['hasSideEffects' => true],
+	'mysqli_client_encoding' => ['hasSideEffects' => true],
+	'mysqli_close' => ['hasSideEffects' => true],
+	'mysqli_commit' => ['hasSideEffects' => true],
+	'mysqli_connect' => ['hasSideEffects' => true],
+	'mysqli_connect_errno' => ['hasSideEffects' => true],
+	'mysqli_connect_error' => ['hasSideEffects' => true],
+	'mysqli_data_seek' => ['hasSideEffects' => true],
+	'mysqli_debug' => ['hasSideEffects' => true],
+	'mysqli_dump_debug_info' => ['hasSideEffects' => true],
+	'mysqli_errno' => ['hasSideEffects' => true],
+	'mysqli_error' => ['hasSideEffects' => true],
+	'mysqli_error_list' => ['hasSideEffects' => true],
+	'mysqli_escape_string' => ['hasSideEffects' => true],
+	'mysqli_execute' => ['hasSideEffects' => true],
+	'mysqli_execute_query' => ['hasSideEffects' => true],
+	'mysqli_fetch' => ['hasSideEffects' => true],
+	'mysqli_fetch_all' => ['hasSideEffects' => true],
+	'mysqli_fetch_array' => ['hasSideEffects' => true],
+	'mysqli_fetch_assoc' => ['hasSideEffects' => true],
+	'mysqli_fetch_column' => ['hasSideEffects' => true],
+	'mysqli_fetch_field' => ['hasSideEffects' => true],
+	'mysqli_fetch_lengths' => ['hasSideEffects' => true],
+	'mysqli_fetch_object' => ['hasSideEffects' => true],
+	'mysqli_fetch_row' => ['hasSideEffects' => true],
+	'mysqli_field_count' => ['hasSideEffects' => true],
+	'mysqli_field_seek' => ['hasSideEffects' => true],
+	'mysqli_field_tell' => ['hasSideEffects' => true],
+	'mysqli_free_result' => ['hasSideEffects' => true],
+	'mysqli_get_cache_stats' => ['hasSideEffects' => true],
+	'mysqli_get_charset' => ['hasSideEffects' => true],
+	'mysqli_get_client_info' => ['hasSideEffects' => true],
+	'mysqli_get_client_stats' => ['hasSideEffects' => true],
+	'mysqli_get_client_version' => ['hasSideEffects' => true],
+	'mysqli_get_connection_stats' => ['hasSideEffects' => true],
+	'mysqli_get_host_info' => ['hasSideEffects' => true],
+	'mysqli_get_links_stats' => ['hasSideEffects' => true],
+	'mysqli_get_metadata' => ['hasSideEffects' => true],
+	'mysqli_get_proto_info' => ['hasSideEffects' => true],
+	'mysqli_get_server_info' => ['hasSideEffects' => true],
+	'mysqli_get_server_version' => ['hasSideEffects' => true],
+	'mysqli_get_warnings' => ['hasSideEffects' => true],
+	'mysqli_info' => ['hasSideEffects' => true],
+	'mysqli_init' => ['hasSideEffects' => true],
+	'mysqli_insert_id' => ['hasSideEffects' => true],
+	'mysqli_kill' => ['hasSideEffects' => true],
+	'mysqli_more_results' => ['hasSideEffects' => true],
+	'mysqli_multi_query' => ['hasSideEffects' => true],
+	'mysqli_next_result' => ['hasSideEffects' => true],
+	'mysqli_options' => ['hasSideEffects' => true],
+	'mysqli_param_count' => ['hasSideEffects' => true],
+	'mysqli_ping' => ['hasSideEffects' => true],
+	'mysqli_poll' => ['hasSideEffects' => true],
+	'mysqli_prepare' => ['hasSideEffects' => true],
+	'mysqli_query' => ['hasSideEffects' => true],
+	'mysqli_real_connect' => ['hasSideEffects' => true],
+	'mysqli_real_escape_string' => ['hasSideEffects' => true],
+	'mysqli_real_query' => ['hasSideEffects' => true],
+	'mysqli_reap_async_query' => ['hasSideEffects' => true],
+	'mysqli_refresh' => ['hasSideEffects' => true],
+	'mysqli_release_savepoint' => ['hasSideEffects' => true],
+	'mysqli_report' => ['hasSideEffects' => true],
+	'mysqli_rollback' => ['hasSideEffects' => true],
+	'mysqli_savepoint' => ['hasSideEffects' => true],
+	'mysqli_select_db' => ['hasSideEffects' => true],
+	'mysqli_send_long_data' => ['hasSideEffects' => true],
+	'mysqli_set_charset' => ['hasSideEffects' => true],
+	'mysqli_set_local_infile_default' => ['hasSideEffects' => true],
+	'mysqli_set_local_infile_handler' => ['hasSideEffects' => true],
+	'mysqli_set_opt' => ['hasSideEffects' => true],
+	'mysqli_sqlstate' => ['hasSideEffects' => true],
+	'mysqli_ssl_set' => ['hasSideEffects' => true],
+	'mysqli_stat' => ['hasSideEffects' => true],
+	'mysqli_stmt_affected_rows' => ['hasSideEffects' => true],
+	'mysqli_stmt_attr_get' => ['hasSideEffects' => true],
+	'mysqli_stmt_attr_set' => ['hasSideEffects' => true],
+	'mysqli_stmt_bind_param' => ['hasSideEffects' => true],
+	'mysqli_stmt_bind_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_close' => ['hasSideEffects' => true],
+	'mysqli_stmt_data_seek' => ['hasSideEffects' => true],
+	'mysqli_stmt_errno' => ['hasSideEffects' => true],
+	'mysqli_stmt_error' => ['hasSideEffects' => true],
+	'mysqli_stmt_error_list' => ['hasSideEffects' => true],
+	'mysqli_stmt_execute' => ['hasSideEffects' => true],
+	'mysqli_stmt_fetch' => ['hasSideEffects' => true],
+	'mysqli_stmt_field_count' => ['hasSideEffects' => true],
+	'mysqli_stmt_free_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_get_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_get_warnings' => ['hasSideEffects' => true],
+	'mysqli_stmt_init' => ['hasSideEffects' => true],
+	'mysqli_stmt_insert_id' => ['hasSideEffects' => true],
+	'mysqli_stmt_more_results' => ['hasSideEffects' => true],
+	'mysqli_stmt_next_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_num_rows' => ['hasSideEffects' => true],
+	'mysqli_stmt_param_count' => ['hasSideEffects' => true],
+	'mysqli_stmt_prepare' => ['hasSideEffects' => true],
+	'mysqli_stmt_reset' => ['hasSideEffects' => true],
+	'mysqli_stmt_result_metadata' => ['hasSideEffects' => true],
+	'mysqli_stmt_send_long_data' => ['hasSideEffects' => true],
+	'mysqli_stmt_sqlstate' => ['hasSideEffects' => true],
+	'mysqli_stmt_store_result' => ['hasSideEffects' => true],
+	'mysqli_store_result' => ['hasSideEffects' => true],
+	'mysqli_thread_id' => ['hasSideEffects' => true],
+	'mysqli_thread_safe' => ['hasSideEffects' => true],
+	'mysqli_use_result' => ['hasSideEffects' => true],
+	'mysqli_warning_count' => ['hasSideEffects' => true],
 	'ob_clean' => ['hasSideEffects' => true],
 	'ob_end_clean' => ['hasSideEffects' => true],
 	'ob_end_flush' => ['hasSideEffects' => true],
diff --git a/resources/functionMetadata.php b/resources/functionMetadata.php
index a01a7181a6e..2d5fbeda3dd 100644
--- a/resources/functionMetadata.php
+++ b/resources/functionMetadata.php
@@ -1392,6 +1392,118 @@
 	'msgfmt_parse_message' => ['hasSideEffects' => false],
 	'mt_getrandmax' => ['hasSideEffects' => false],
 	'mt_rand' => ['hasSideEffects' => true],
+	'mysqli_affected_rows' => ['hasSideEffects' => true],
+	'mysqli_autocommit' => ['hasSideEffects' => true],
+	'mysqli_begin_transaction' => ['hasSideEffects' => true],
+	'mysqli_bind_param' => ['hasSideEffects' => true],
+	'mysqli_bind_result' => ['hasSideEffects' => true],
+	'mysqli_change_user' => ['hasSideEffects' => true],
+	'mysqli_character_set_name' => ['hasSideEffects' => true],
+	'mysqli_client_encoding' => ['hasSideEffects' => true],
+	'mysqli_close' => ['hasSideEffects' => true],
+	'mysqli_commit' => ['hasSideEffects' => true],
+	'mysqli_connect' => ['hasSideEffects' => true],
+	'mysqli_connect_errno' => ['hasSideEffects' => true],
+	'mysqli_connect_error' => ['hasSideEffects' => true],
+	'mysqli_data_seek' => ['hasSideEffects' => true],
+	'mysqli_debug' => ['hasSideEffects' => true],
+	'mysqli_dump_debug_info' => ['hasSideEffects' => true],
+	'mysqli_errno' => ['hasSideEffects' => true],
+	'mysqli_error' => ['hasSideEffects' => true],
+	'mysqli_error_list' => ['hasSideEffects' => true],
+	'mysqli_escape_string' => ['hasSideEffects' => true],
+	'mysqli_execute' => ['hasSideEffects' => true],
+	'mysqli_execute_query' => ['hasSideEffects' => true],
+	'mysqli_fetch' => ['hasSideEffects' => true],
+	'mysqli_fetch_all' => ['hasSideEffects' => true],
+	'mysqli_fetch_array' => ['hasSideEffects' => true],
+	'mysqli_fetch_assoc' => ['hasSideEffects' => true],
+	'mysqli_fetch_column' => ['hasSideEffects' => true],
+	'mysqli_fetch_field' => ['hasSideEffects' => true],
+	'mysqli_fetch_lengths' => ['hasSideEffects' => true],
+	'mysqli_fetch_object' => ['hasSideEffects' => true],
+	'mysqli_fetch_row' => ['hasSideEffects' => true],
+	'mysqli_field_count' => ['hasSideEffects' => true],
+	'mysqli_field_seek' => ['hasSideEffects' => true],
+	'mysqli_field_tell' => ['hasSideEffects' => true],
+	'mysqli_free_result' => ['hasSideEffects' => true],
+	'mysqli_get_cache_stats' => ['hasSideEffects' => true],
+	'mysqli_get_charset' => ['hasSideEffects' => true],
+	'mysqli_get_client_info' => ['hasSideEffects' => true],
+	'mysqli_get_client_stats' => ['hasSideEffects' => true],
+	'mysqli_get_client_version' => ['hasSideEffects' => true],
+	'mysqli_get_connection_stats' => ['hasSideEffects' => true],
+	'mysqli_get_host_info' => ['hasSideEffects' => true],
+	'mysqli_get_links_stats' => ['hasSideEffects' => true],
+	'mysqli_get_metadata' => ['hasSideEffects' => true],
+	'mysqli_get_proto_info' => ['hasSideEffects' => true],
+	'mysqli_get_server_info' => ['hasSideEffects' => true],
+	'mysqli_get_server_version' => ['hasSideEffects' => true],
+	'mysqli_get_warnings' => ['hasSideEffects' => true],
+	'mysqli_info' => ['hasSideEffects' => true],
+	'mysqli_init' => ['hasSideEffects' => true],
+	'mysqli_insert_id' => ['hasSideEffects' => true],
+	'mysqli_kill' => ['hasSideEffects' => true],
+	'mysqli_more_results' => ['hasSideEffects' => true],
+	'mysqli_multi_query' => ['hasSideEffects' => true],
+	'mysqli_next_result' => ['hasSideEffects' => true],
+	'mysqli_options' => ['hasSideEffects' => true],
+	'mysqli_param_count' => ['hasSideEffects' => true],
+	'mysqli_ping' => ['hasSideEffects' => true],
+	'mysqli_poll' => ['hasSideEffects' => true],
+	'mysqli_prepare' => ['hasSideEffects' => true],
+	'mysqli_query' => ['hasSideEffects' => true],
+	'mysqli_real_connect' => ['hasSideEffects' => true],
+	'mysqli_real_escape_string' => ['hasSideEffects' => true],
+	'mysqli_real_query' => ['hasSideEffects' => true],
+	'mysqli_reap_async_query' => ['hasSideEffects' => true],
+	'mysqli_refresh' => ['hasSideEffects' => true],
+	'mysqli_release_savepoint' => ['hasSideEffects' => true],
+	'mysqli_report' => ['hasSideEffects' => true],
+	'mysqli_rollback' => ['hasSideEffects' => true],
+	'mysqli_savepoint' => ['hasSideEffects' => true],
+	'mysqli_select_db' => ['hasSideEffects' => true],
+	'mysqli_send_long_data' => ['hasSideEffects' => true],
+	'mysqli_set_charset' => ['hasSideEffects' => true],
+	'mysqli_set_local_infile_default' => ['hasSideEffects' => true],
+	'mysqli_set_local_infile_handler' => ['hasSideEffects' => true],
+	'mysqli_set_opt' => ['hasSideEffects' => true],
+	'mysqli_sqlstate' => ['hasSideEffects' => true],
+	'mysqli_ssl_set' => ['hasSideEffects' => true],
+	'mysqli_stat' => ['hasSideEffects' => true],
+	'mysqli_stmt_affected_rows' => ['hasSideEffects' => true],
+	'mysqli_stmt_attr_get' => ['hasSideEffects' => true],
+	'mysqli_stmt_attr_set' => ['hasSideEffects' => true],
+	'mysqli_stmt_bind_param' => ['hasSideEffects' => true],
+	'mysqli_stmt_bind_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_close' => ['hasSideEffects' => true],
+	'mysqli_stmt_data_seek' => ['hasSideEffects' => true],
+	'mysqli_stmt_errno' => ['hasSideEffects' => true],
+	'mysqli_stmt_error' => ['hasSideEffects' => true],
+	'mysqli_stmt_error_list' => ['hasSideEffects' => true],
+	'mysqli_stmt_execute' => ['hasSideEffects' => true],
+	'mysqli_stmt_fetch' => ['hasSideEffects' => true],
+	'mysqli_stmt_field_count' => ['hasSideEffects' => true],
+	'mysqli_stmt_free_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_get_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_get_warnings' => ['hasSideEffects' => true],
+	'mysqli_stmt_init' => ['hasSideEffects' => true],
+	'mysqli_stmt_insert_id' => ['hasSideEffects' => true],
+	'mysqli_stmt_more_results' => ['hasSideEffects' => true],
+	'mysqli_stmt_next_result' => ['hasSideEffects' => true],
+	'mysqli_stmt_num_rows' => ['hasSideEffects' => true],
+	'mysqli_stmt_param_count' => ['hasSideEffects' => true],
+	'mysqli_stmt_prepare' => ['hasSideEffects' => true],
+	'mysqli_stmt_reset' => ['hasSideEffects' => true],
+	'mysqli_stmt_result_metadata' => ['hasSideEffects' => true],
+	'mysqli_stmt_send_long_data' => ['hasSideEffects' => true],
+	'mysqli_stmt_sqlstate' => ['hasSideEffects' => true],
+	'mysqli_stmt_store_result' => ['hasSideEffects' => true],
+	'mysqli_store_result' => ['hasSideEffects' => true],
+	'mysqli_thread_id' => ['hasSideEffects' => true],
+	'mysqli_thread_safe' => ['hasSideEffects' => true],
+	'mysqli_use_result' => ['hasSideEffects' => true],
+	'mysqli_warning_count' => ['hasSideEffects' => true],
 	'net_get_interfaces' => ['hasSideEffects' => false],
 	'ngettext' => ['hasSideEffects' => false],
 	'nl2br' => ['hasSideEffects' => false],
diff --git a/tests/PHPStan/Rules/Comparison/BooleanOrConstantConditionRuleTest.php b/tests/PHPStan/Rules/Comparison/BooleanOrConstantConditionRuleTest.php
index cc628575f79..31397bf28b0 100644
--- a/tests/PHPStan/Rules/Comparison/BooleanOrConstantConditionRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/BooleanOrConstantConditionRuleTest.php
@@ -384,4 +384,11 @@ public function testBug10305(): void
 		]);
 	}
 
+	public function testBug14473(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/bug-14473.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-14473.php b/tests/PHPStan/Rules/Comparison/data/bug-14473.php
new file mode 100644
index 00000000000..c45fa4c05e5
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-14473.php
@@ -0,0 +1,27 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14473;
+
+$link = mysqli_connect('host', 'user', 'pass', 'database') or die('Could not connect: ' . mysqli_connect_error());
+
+// (assume long-running code that can cause the connection to time out)
+
+$link = mysqli_connect('host', 'user', 'pass', 'database') or die('Could not reconnect: ' . mysqli_connect_error());
+
+// okay, so let's make certain that the connection is closed
+mysqli_close($link);
+
+$link = mysqli_connect('host', 'user', 'pass', 'database') or die('Could not reconnect: ' . mysqli_connect_error());
+
+// close it and destroy the variable
+mysqli_close($link);
+unset($link);
+
+$link = mysqli_connect('host', 'user', 'pass', 'database') or die('Could not reconnect: ' . mysqli_connect_error());
+
+// close, destroy ...
+mysqli_close($link);
+unset($link);
+
+// ... and assign to a different variable
+$newLink = mysqli_connect('host', 'user', 'pass', 'database') or die('Could not reconnect: ' . mysqli_connect_error());