Tested versions

Reproducible in 2ba22d1 (fairly recent master branch build)
Reproducible in v4.3.dev6

System information

Windows 10.0.19044 - dedicated NVIDIA GeForce RTX 2080 (NVIDIA; 31.0.15.5186) - Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz (12 Threads)

Issue description

A preload expression causes static constructor and variable initializers to run.
However, writing a preload on a standalone line still causes this warning:

Standalone expression (the line has no effect). (STANDALONE_EXPRESSION)

This is already accounted for with load, which does not show a warning in this situation.

Steps to reproduce

In your scene:

extends Node

func _ready() -> void:
	# This has side effects!
	preload("res://static_stuff.gd")

And in static_stuff.gd:

extends Object

static func _static_init() -> void:
	print("side effect 1")

static var static_var = compute()

static func compute():
	print("side effect 2")
	return 5

Despite the STANDALONE_EXPRESSION warning showing, you will see two prints in Output. The warning is not correct here!

Minimal reproduction project (MRP)

preload-standalone-expression.zip