From the root of your project, write the following in the .vscode/settings.json file:
{
"rust-analyzer.check.overrideCommand": [
"cargo",
"creusot",
"--",
"--message-format=json"
]
}
For other editors, see https://rust-analyzer.github.io/book/other_editors.html to add the above option to your configuration.
Note that you will probably want to enable this option only in projects that use creusot.