Typescript: Always-false-condition in editorServices.ts

[vilchik-elena]

The condition on line 1663 in editorServices.ts:
https://github.com/Microsoft/TypeScript/blob/eef7d8bd3d974528464c7968deab78b747568c06/src/server/editorServices.ts#L1650-L1666

is always false as the called method closeExternalProject always returns void. That way the if-block with shouldRefreshInferredProjects = true; is never executed (for more information see the linter rule detecting this).

[andy-ms]

See also https://palantir.github.io/tslint/rules/no-void-expression/ -- but this would require us to set up linting with type information.

[mhegazy]

thanks for the report. a PR would be appreciated.

[RyanCavanaugh]

@mhegazy seems like using a void value in a truthiness position is hyper-sketchy - thoughts on making that an error in TS?

[mhegazy]

thoughts on making that an error in TS?

i thought you had experimented with this a while back; I think it is a check worth adding, baring any breaks that we might find from RWC tests.

[RyanCavanaugh]

I had a test for always-truthy values that attempted to find bugs like if (x.f) (in lieu of if (x.f()) {) but the problem was that non-strictNullChecks .d.ts file gave tons of false positives. Checking for void values in control flow test positions should be a home run

[mhegazy]

i think the void check should only flag errors. seems like a low risk-high yield change to make.