[Bug]: When building a path through an existing one, the path is also laid under bridges

[DefinitelyNotRau117]

Version of OpenTTD

OpenTTD 20231121; Windows 10

Expected result

The area under/after the bridge is not affected, the rails/roads are laid up to the first tile of the bridge

Actual result

The first time everything works as it should, but if you re-lay tracks through an existing one, the tracks will be laid under the bridge.

2023-12-02.19-37-37.mp4

The bug also appears on roads, tunnels and diagonal tracks.

2023-12-02.19-35-26.mp4

2023-12-02.19-50-19.mp4

Steps to reproduce

1. Build a bridge and a path across it
2. Pass the new path through existing one again

[JGRennison]

This functionality change was made by #11089

[DefinitelyNotRau117]

This functionality change was made by #11089

This is not what the bug report is about, for the first time, building before the bridge is working as expected.
This bug report that if you do this a second time, the rails will be built below the bridge.

For example, this could result in signals being removed under a bridge. And if there is a programmable signal under the bridge, this may become a more intrusive problem.

2023-12-03.01-30-19.mp4

[JGRennison]

This functionality change was made by #11089

This is not what the bug report is about, for the first time, building before the bridge is working as expected. This bug report that if you do this a second time, the rails will be built below the bridge.

On the contrary, the change in #11089 is what what this bug report is about. If you revert that commit then the bug as you've described it disappears.
To spell it out, the bridge head tile is the "invalid tile" as mentioned in #11089, and the whole purpose of #11089 is to allow the sort of behaviour which is described in this bug. Whether this is actually good/useful is a separate question.

[PeterN]

#11089 is the cause of this issue but that doesn't mean this specific behaviour with bridges is intentional.

IMHO, building over a bridge ramp from one side to another should continue after it, and building from underneath the bridge should continue until the bridge ramp.

[Eddi-z]

I agree with @PeterN here, this behaviour seems neither intuitive nor helpful.