[iOS] - Replace NOTREACHED_IN_MIGRATION for iOS

[Brandon-T]

• Replace NOTREACHED_IN_MIGRATION for iOS. Replaced with CHECK, DCHECK, [[no_return]] where necessary.

Resolves brave/brave-browser#41886

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally:
  • npm run test -- brave_browser_tests, npm run test -- brave_unit_tests wiki
  • npm run presubmit wiki, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[boocmp]

Shouldn't it just become NOTREACHED()?

[cdesouza-chromium]

Hey Brandon, I think we will need to review the guidance to correct this PR[1]. NOTREACHED is now [[noreturn]] and so you should assume that a failed CHECK/DCHECK won't return, so we shouldn't have code after it for the failure path. A few examples on the guidance of "bad" code are like this:

// Bad:
//
// Do not handle `DCHECK()` failures. Use `CHECK()` instead and omit the
// conditional below.
DCHECK(foo);  // Use CHECK() instead and omit conditional below.
if (!foo) {
  ...
}

// Bad:
//
// Use CHECK(bar); instead.
if (!bar) {
  NOTREACHED();
}

We shouldn't be doing CHECK(FALSE) as that should be NOTREACHED. A CHECK is a NOTREACHED with a conditional in a way.

[1] https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/checks.md

[Brandon-T]

NOTREACHED

Fixed.

However, chromium doesn't seem to be doing the same: https://source.chromium.org/chromium/chromium/src/+/main:chrome/browser/bookmarks/bookmark_html_writer.cc;l=338?q=BookmarkCodec::kTypeFolder&ss=chromium%2Fchromium%2Fsrc

They have:

if (!url_string) {
    NOTREACHED_IN_MIGRATION();
    return false;
}

instead of:

CHECK(url_string);

[cdesouza-chromium]

NOTREACHED

Chromium doesn't seem to be doing the same: https://source.chromium.org/chromium/chromium/src/+/main:chrome/browser/bookmarks/bookmark_html_writer.cc;l=338?q=BookmarkCodec::kTypeFolder&ss=chromium%2Fchromium%2Fsrc

They have:

if (!url_string) {
    NOTREACHED_IN_MIGRATION();
    return false;
}

instead of:

CHECK(url_string);

Please read the document.

[cdesouza-chromium]

Thanks Brandon for that. Looks good.

[brave-builds]

Released in v1.73.51