ICU symbol resolution fails on Linux with versioned exports

[frostney]

Summary

On Linux, ICU libraries export versioned symbols (e.g. unum_open_76 instead of unum_open). ICUGetProcAddress in source/shared/ICU.pas looks up bare names only, so all symbol resolution fails silently and ICU is never loaded. All Intl formatting falls through to the CLDR path.

Why

The CLDR fallback lacks significant digits, rounding modes, rounding increments, collation sensitivity, proper datetime formatting, and locale-aware canonicalization. With ICU disabled, ~50+ intl402 test262 tests that depend on correct ICU behavior either fail or pass vacuously.

Current behavior

# On Ubuntu 25.04 with ICU 76:
nm -D /lib/aarch64-linux-gnu/libicui18n.so.76 | grep "T unum_open"
# 00000000002ccd80 T unum_open_76    (versioned, no bare alias)

TryLoadLinuxICU loads libicui18n.so.76 successfully, but every GetProcAddress(Handle, 'unum_open') call returns nil. TryLoadIntlFunctions returns False.

Expected behavior

ICUGetProcAddress should try the versioned name (unum_open_76) when the bare lookup fails. The version suffix is already known from TryLoadLinuxICU which iterates ICU_VERSION_MAX downto ICU_VERSION_MIN.

Scope notes

• Fix is in source/shared/ICU.pas: store the discovered version suffix during TryLoadLinuxICU and append it in ICUGetProcAddress when the bare name isn't found.
• Enabling ICU on Linux unmasks 7 pre-existing ICU integration bugs that were hidden while ICU was disabled. These need to be fixed alongside or after the symbol fix:
  • intl402/Collator/prototype/compare/non-normative-basic.js
  • intl402/Collator/prototype/compare/non-normative-sensitivity.js
  • intl402/DateTimeFormat/prototype/format/offset-timezone-gmt-same.js
  • intl402/DateTimeFormat/prototype/formatToParts/related-year-zh.js
  • intl402/DateTimeFormat/prototype/formatToParts/time-clip-to-integer.js
  • intl402/Intl/getCanonicalLocales/grandfathered.js
  • intl402/supportedLocalesOf-unicode-extensions-ignored.js
• Related: Intl: resolvedOptions() missing required fields across all constructors #595, Intl: NumberFormat options not applied to ICU formatter #598, NumberFormat roundingIncrement precision loss for large increments and missing roundingPriority #635.

[frostney]

Root cause analysis for the 7 unmasked ICU integration bugs

Reproduced on Orbstack Ubuntu 25.04 (questing) with ICU 76.1. Error messages from each test:

1. getCanonicalLocales/grandfathered.js

Expected SameValue(«cmn», «zh») to be true

ICU 76 canonicalizes zh-guoyu → cmn (Mandarin Chinese), but ECMA-402/CLDR expects zh. The TryICUCanonicalizeLocale path runs first and returns ICU's result. Fix: post-process ICU canonical output through the CLDR grandfathered tag table, or apply known overrides.

2. Collator/prototype/compare/non-normative-basic.js

Expected array element 1 to be SameValue(C, b)

ICU sorts lowercase before uppercase at tertiary strength (Unicode default). The test expects uppercase-first ordering (A, b, C, d, ...). Fix: set UCOL_CASE_FIRST attribute to UCOL_UPPER_FIRST when the locale's default collation expects it, or investigate whether the collation locale extension should be passed through.

3. DateTimeFormat/prototype/format/offset-timezone-gmt-same.js

+0300 vs. Etc/GMT-3: Expected SameValue(«12/17/95, 3:24 AM», «12/17/95, 6:24 AM») to be true

Offset timezone +0300 and Etc/GMT-3 should produce identical output. ICU formats +0300 as 3:24 AM (UTC time) instead of 6:24 AM (UTC+3 local time). The timezone string is passed to udat_open but may not be parsed correctly as an offset.

4. DateTimeFormat/prototype/formatToParts/time-clip-to-integer.js

formatToParts(-0.9) Expected SameValue(«Dec 31, 1969, 11:59:59 PM», «Jan 1, 1970, 12:00:00 AM») to be true

ECMA-402 requires TimeClip to truncate millisecond values toward zero before formatting. -0.9 ms should be treated as 0 ms (epoch). The engine passes -0.9 directly to ICU which formats it as the previous day.

5. DateTimeFormat/prototype/formatToParts/related-year-zh.js

Not debugged yet — likely requires Chinese calendar support in ICU integration.

6. supportedLocalesOf-unicode-extensions-ignored.js

Times out — likely an infinite loop or O(n²) in the locale matching when ICU returns a large list of available locales (~700+).

7. Collator/prototype/compare/non-normative-sensitivity.js

Related to 2 — ICU collation attribute configuration for sensitivity levels.