Strictify on all layers

[turt2live]

Why?

The non-strict aspects of TypeScript allow for a lot of flexibility but also make it easy for errors to slip in, e.g. when there is no strong contract on null-ness.

What?

We’ll fix all existing strict-mode violations and enable all strict-mode checks to run on PRs. This will allow us to eliminate entire classes of errors through static code analysis.

Reference: https://www.typescriptlang.org/tsconfig#strict

Plan

matrix-js-sdk

Beta Give feedback

1. Enable strict in matrix-js-sdk

matrix-react-sdk

Beta Give feedback

1. Enable noImplicitThis in matrix-react-sdk
2. Enable strictBindCallApply in matrix-react-sdk
3. Enable alwaysStrict in matrix-react-sdk
4. Enable noImplicitAny for matrix-js-sdk and matrix-react-sdk vector-im/element-web#21968
   A-Developer-Experience A-Testing T-Enhancement +3
   
5. Use strictNullChecks in matrix-react-sdk vector-im/element-web#21967
   54 of 54
   A-Developer-Experience A-Testing T-Enhancement Z-MadLittleMods +4
   
6. Enable strictFunctionTypes in matrix-react-sdk
7. Enable strictPropertyInitialization in matrix-react-sdk
8. Enable useUnknownInCatchVariables in matrix-react-sdk
9. Enable noUnusedLocals in matrix-react-sdk
10. Enable strict in matrix-react-sdk

element-web

Beta Give feedback

1. Enable noImplicitThis in element-web
2. Enable strictBindCallApply in element-web
3. Enable alwaysStrict in element-web
4. Enable noImplicitAny in element-web
5. Enable strictNullChecks in element-web
6. Enable strictFunctionTypes in element-web
7. Enable strictPropertyInitialization in element-web
8. Enable useUnknownInCatchVariables in element-web
9. Enable noUnusedLocals in element-web
10. Enable strict in element-web

element-desktop

Beta Give feedback

1. Enable strict in element-desktop

[Johennes]

@t3chguy did a quick pulse-check of what's left in matrix-react-sdk right now:

Strict attribute	Errors	Files
useUnknownInCatchVariables	151	64
strictFunctionTypes	102	57
strictNullChecks	4749	699
strictPropertyInitialization	167	~20

Note that strictPropertyInitialization cannot be enabled until strictNullChecks is enabled.

We also have some statistics on https://arewetsyet.bit.ovh/ but they're currently broken.

[t3chguy]

noImplicitAny cannot be enabled until strictNullChecks either in our case due to some of the js-sdk relying on the strict parser for implicit typing

[t3chguy]

I am making good progress with strictNullChecks - down to 2645 errors in 400 files

[paboum]

The non-strict aspects of TypeScript allow for a lot of flexibility but also make it easy for errors to slip in, e.g. when there is no strong contract on null-ness.

I never understood the so called "front end" programming, but it seems to me this is basically removal of https://en.wikipedia.org/wiki/Undefined_behavior and, as such, a technical debt. It is somewhat interesting how new generations of programmers believe they can "solve" the issues of having to controlling the flow by selectively ignoring it, but luckily, everyone learns it is unavoidable sooner or later.

Though I cannot contribute here due to lack of js/ts expertise, I would like to cheer @t3chguy up, if you find any errors that cannot simply be solved by single line edits, you will probably be able to isolate meaningful bug reports for others to resolve, or even find specification omissions that will impact other projects. It's better if you do it, not the users filing bug reports, so your effort matters.