Extension TerminalLinkProvider cannot detect links in reused task terminals

[ashgti]

Does this issue occur when all extensions are disabled? Yes

Version: 1.61.0
Commit: ee8c7de
Date: 2021-10-07T18:11:58.853Z
Electron: 13.5.1
Chrome: 91.0.4472.164
Node.js: 14.16.0
V8: 9.1.269.39-electron.0
OS: Darwin x64 20.6.0

Steps to Reproduce:

1. Run the Terminal Sample from the vscode-extension-sample repository https://github.com/microsoft/vscode-extension-samples/blob/main/terminal-sample
2. Invoke the terminalTest.registerTerminalLinkProvider
3. Trigger a task that reuses a terminal. For example, I used a user task like:

        {
            "type": "shell",
            "label": "Say Hello",
            "command": [
                "echo link hello!"
            ],
            "problemMatcher": []
        }

On the first run of the task the 'link' text will create a hover link correctly. If you re-run the task so the terminal has 2 (or more) runs of the task in the same terminal then the link will fail to detect correctly.

Adding a breakpoint to https://github.com/microsoft/vscode-extension-samples/blob/main/terminal-sample/src/extension.ts#L162 there appears to be 1 call per execution of the task in the terminal. I think when the terminal is re-used it re-registers the link provider and if two link providers have overlapping links they both seem to fail (which is a known issue #97070 but due to this bug all link providers start failing if tasks are run multiple times).

[ashgti]

Putting a breakpoint in the registerLinkProvider call for xterm (here https://github.com/microsoft/vscode/blob/main/src/vs/workbench/contrib/terminal/browser/links/terminalLinkManager.ts#L150) I see multiple copies of all of the link providers: