ref(build): Turn on `isolatedModules` TS option #4497

lobsterkatie · 2022-02-03T19:52:05Z

This applies the TypeScript isolatedModules setting to all packages in the repo, which is necessary in order for us to use any compiler other than tsc. (All other compilers handle each file separately, without understanding the relationships between them the way tsc does, so we need TS to warn us if we're doing anything which would make that a problem).

It also makes two code changes necessary in order to be compatible with the isolatedModules flag, specifically:

All re-exported types and interfaces (anything that will get stripped away when compiling from TS to JS) are now exported using export type. This lets non-tsc compilers know that the exported types are eligible for stripping, in spite of the fact that said compilers can't follow the export path backwards to see the types' implementation.
Usages of the Severity enum from @sentry/types were replaced with string literals, which was necessary here because non-tsc compilers can't trace usages of a const enum back to their underlying values to do the substitution. They therefore leave those usages alone, while at the same time stripping the enum definitions the way tsc would. This leads to usages of something which no longer exists, which is obviously a problem. Using the string literals prevents that.

github-actions · 2022-02-03T20:00:23Z

size-limit report

Path	Base Size (ad37109)	Current Size	Change
@sentry/browser - CDN Bundle (gzipped)	19.68 KB	19.68 KB	+0.01% 🔺
@sentry/browser - CDN Bundle (minified)	62.89 KB	62.87 KB	-0.05% 🔽
@sentry/browser - Webpack	22.21 KB	22.21 KB	-0.02% 🔽
@sentry/browser - Webpack - gzip = false	76.02 KB	76.04 KB	+0.03% 🔺
@sentry/react - Webpack	22.24 KB	22.24 KB	-0.02% 🔽
@sentry/nextjs Client - Webpack	46.24 KB	46.27 KB	+0.08% 🔺
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	28.22 KB	28.23 KB	+0.04% 🔺

Note: This and #4896 are together a (slightly updated) repeat of #4497, to get it onto the main v7 branch. Our original v7 plan called for deprecating and then removing the `Severity` enum which lives in `@sentry/types`, because enums transpile to a two-way lookup function with a fairly hefty footprint (see this SO answer[1] from one of the maintainers of TS). We therefore added a new `SeverityLevel` type, which is the union of all of `Severity`'s underlying values, and directed people to use that instead. Though we subsequently decided not to remove `Severity` (at least in v7), we agreed that we should stop using it internally. This implements that change. Key Changes: - `Severity` and `severityFromString` have been redeprecated. - The original plan to have `SeverityLevel` live in `@sentry/utils` has been reverted, and it now lives only in `@sentry/types`. - The internal `SeverityLevels` array on which we were basing `SeverityLevel` has been removed. While we lose the elegance of the derived type, we gain the ability to truly only export types from `@sentry/types`. - Wherever we accept a `Severity` value, we now also accept a `SeverityLevel`. - All internal uses of `Severity` values have been replaced with the equivalent string constants. - A new `severityLevelFromString` function has been introduced, and is now used in place of `SeverityFromString`. - The tests for `severityFromString` have been cleaned up and replaced with equivalent tests for `SeverityLevelFromString`. [1] https://stackoverflow.com/a/28818850

Note: This and #4926 are together a (slightly updated) repeat of #4497, to get it onto the main v7 branch. This applies [the TypeScript `isolatedModules` setting[1] to all packages in the repo, which is necessary in order for us to use any compiler other than `tsc`. (All other compilers handle each file separately, without understanding the relationships between them the way `tsc` does, so we need TS to warn us if we're doing anything which would make that a problem). It also makes the second of two code changes necessary in order to be compatible with the `isolatedModules` flag: all re-exported types and interfaces (anything that will get stripped away when compiling from TS to JS) are now exported using `export type`. This lets non-`tsc` compilers know that the exported types are eligible for stripping, in spite of the fact that said compilers can't follow the export path backwards to see the types' implementation. (The other code change, eliminating our usage of the `Severity` enum, was split off into the PR linked above.) [1] https://www.typescriptlang.org/tsconfig#isolatedModules