commit 387feacbf4dc4ca94e4a764a32a7c1dd45d913f2
author dpapad <dpapad@chromium.org> Thu Jul 15 23:13:08 2021
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Jul 15 23:13:08 2021
tree 9d8d243cbbddac4bb276d95c3481574b19e8015c
parent 15e46773148f209b8936be6d8cfc0a7bdf8a61b8

WebUI: Remove "incremental" flag from default tsconfig_base.json.

The incremental flag is causing issues where stale output is picked up
by the build, leading to flaky tests when switching between branches or
when bots switch between patches.

Under the cover, with incremental builds TS generates a .tsbuildinfo
file that holds metadata (hashes) about the input files. When switching
between git branches (or patches) the build can get into a state where
TS compiler looks at the .tsbuildinfo file and sees that none of the
source files have changed.

For example performing the following sequence, with specially crafted
branches, can cause a bad build:

1) Switch to branchA -> build
   .tsbuildinfo info is generated
2) Switch to branchB -> build
   .tsbuildinfo is ignored, but remains in the gen/ folder, other
   generated files modified/deleted
3) Switch to branchA -> build
   .tsbuildinfo from #1 causes the TS Compiler to not re-generate
   its output.

TS compiler doesn't check whether the output files have been modified
or even deleted, leaving the build with either stale or missing files
respectively.

Removing the |incremental| flag fixes the issue, and TS compiler always
re-generates its output, whenever GN decides that the ts_library()
target is dirty, which correctly takes into account whether output files
have been modified or deleted.

Bug: 1229303
Fixed: 1229235
Change-Id: I17a1297f3283bb4ad592aec78927b10cfa74d395
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3032602
Auto-Submit: dpapad <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#902216}