Ensure optional value normalizing is correct for index

[ijjk]

This fixes a case where optional catch-all route values aren't normalized to an array properly when the index value is passed. An additional test case has been added to prevent regressing on this.

x-ref: slack thread

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
buildDuration	16.6s	17.5s	⚠️ +912ms
buildDurationCached	4.5s	4.1s	-422ms
nodeModulesSize	355 MB	355 MB	⚠️ +165 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.092	4.434	⚠️ +0.34
/ avg req/sec	610.94	563.85	⚠️ -47.09
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.213	2.055	-0.16
/error-in-render avg req/sec	1129.56	1216.71	+87.15

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	27.2 kB	27.2 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71 kB	71 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	326 B	326 B	✓
dynamic-HASH.js gzip	2.37 kB	2.37 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	919 B	919 B	✓
image-HASH.js gzip	4.87 kB	4.87 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.13 kB	2.13 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.2 kB	14.2 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
index.html gzip	530 B	530 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
buildDuration	20.8s	20.7s	-71ms
buildDurationCached	4.2s	4.1s	-96ms
nodeModulesSize	355 MB	355 MB	⚠️ +165 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.063	4.091	⚠️ +0.03
/ avg req/sec	615.27	611.1	⚠️ -4.17
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.101	2.106	0
/error-in-render avg req/sec	1189.92	1187.04	⚠️ -2.88

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	27.3 kB	27.3 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.3 kB	71.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.36 kB	2.36 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	911 B	911 B	✓
image-HASH.js gzip	4.89 kB	4.89 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.19 kB	2.19 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.2 kB	14.2 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js fix/optional-value-normalizing	Change
index.html gzip	531 B	531 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: ddd0cf3