[SR-9985] TestNSNumber.test_descriptionWithLocale failing on Swift 5.0 AArch64

[futurejones]

Previous ID	SR-9985
Radar	None
Original Reporter	@futurejones
Type	Bug
Status	Resolved
Resolution	Done

Environment

Linux Ubuntu 16.04 LTS on AArch64

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	None
Priority	Medium

md5: 5d44a74d8f8f63c16353924e5b1e3d3c

Issue Description:

In Swift 4.2.2 `TestNSNumber.test_descriptionWithLocale` passes.

Test Case 'TestNSNumber.test_descriptionWithLocale' started at 2019-02-06 01:42:36.492
 Test Case 'TestNSNumber.test_descriptionWithLocale' passed (0.001 seconds)

But in Swift 5.0 `TestNSNumber.test_descriptionWithLocale` fails.

Test Case 'TestNSNumber.test_descriptionWithLocale' started at 2019-02-23 05:20:56.122
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1105: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000") is not equal to ("1,000") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1110: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-32768") is not equal to ("-32,768") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1111: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("32767") is not equal to ("32,767") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1112: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-2147483648") is not equal to ("-2,147,483,648") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1113: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("2147483647") is not equal to ("2,147,483,647") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1114: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-9223372036854775808") is not equal to ("-9,223,372,036,854,775,808") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1115: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("9223372036854775807") is not equal to ("9,223,372,036,854,775,807") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1120: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("65535") is not equal to ("65,535") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1122: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("4294967295") is not equal to ("4,294,967,295") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1130: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1e+09") is not equal to ("1E+09") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1133: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1134: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1.175494e-38") is not equal to ("1.175494E-38") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1135: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1.401298e-45") is not equal to ("1.401298E-45") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1136: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("3.402823e+38") is not equal to ("3.402823E+38") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1140: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000000000") is not equal to ("1,000,000,000") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1143: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1150: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000") is not equal to ("1.000") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1155: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-32768") is not equal to ("-32.768") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1156: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("32767") is not equal to ("32.767") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1157: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-2147483648") is not equal to ("-2.147.483.648") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1158: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("2147483647") is not equal to ("2.147.483.647") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1159: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-9223372036854775808") is not equal to ("-9.223.372.036.854.775.808") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1160: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("9223372036854775807") is not equal to ("9.223.372.036.854.775.807") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1165: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("65535") is not equal to ("65.535") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1167: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("4294967295") is not equal to ("4.294.967.295") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1175: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1e+09") is not equal to ("1E+09") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1179: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1180: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1,175494e-38") is not equal to ("1,175494E-38") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1181: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1,401298e-45") is not equal to ("1,401298E-45") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1182: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("3,402823e+38") is not equal to ("3,402823E+38") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1185: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000000000") is not equal to ("1.000.000.000") - 
 /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/swift-corelibs-foundation/TestFoundation/TestNSNumber.swift:1188: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 
 Test Case 'TestNSNumber.test_descriptionWithLocale' failed (0.008 seconds)

[spevans]

What version of ICU are you using? Is it building it as part of the swift build?

[futurejones]

As far as I can see it is version ICU4C and it is part of the swift build.

[spevans]

Could you try merging #1866 into your master branch to see if it passes - It checks the ICU version >= 61

Also, could you test if the latest swift-4.2-branch still builds and tests ok, as this fix #1929 was added as a potential fix for 4.2.3 so it may need to be reverted.

[futurejones]

Tested new build of swift-4.2-branch and

TestNSNumber.test_descriptionWithLocale

is now failing.

Test Case 'TestNSNumber.test_descriptionWithLocale' started at 2019-02-23 13:16:22.710

TestFoundation/TestNSNumber.swift:1104: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000") is not equal to ("1,000") - 

TestFoundation/TestNSNumber.swift:1109: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-32768") is not equal to ("-32,768") - 

TestFoundation/TestNSNumber.swift:1110: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("32767") is not equal to ("32,767") - 

TestFoundation/TestNSNumber.swift:1111: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-2147483648") is not equal to ("-2,147,483,648") - 

TestFoundation/TestNSNumber.swift:1112: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("2147483647") is not equal to ("2,147,483,647") - 

TestFoundation/TestNSNumber.swift:1113: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-9223372036854775808") is not equal to ("-9,223,372,036,854,775,808") - 

TestFoundation/TestNSNumber.swift:1114: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("9223372036854775807") is not equal to ("9,223,372,036,854,775,807") - 

TestFoundation/TestNSNumber.swift:1119: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("65535") is not equal to ("65,535") - 

TestFoundation/TestNSNumber.swift:1121: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("4294967295") is not equal to ("4,294,967,295") - 

TestFoundation/TestNSNumber.swift:1129: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1e+09") is not equal to ("1E+09") - 

TestFoundation/TestNSNumber.swift:1132: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 

TestFoundation/TestNSNumber.swift:1133: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1.175494e-38") is not equal to ("1.175494E-38") - 

TestFoundation/TestNSNumber.swift:1134: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1.401298e-45") is not equal to ("1.401298E-45") - 

TestFoundation/TestNSNumber.swift:1135: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("3.402823e+38") is not equal to ("3.402823E+38") - 

TestFoundation/TestNSNumber.swift:1139: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000000000") is not equal to ("1,000,000,000") - 

TestFoundation/TestNSNumber.swift:1142: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 

TestFoundation/TestNSNumber.swift:1149: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000") is not equal to ("1.000") - 

TestFoundation/TestNSNumber.swift:1154: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-32768") is not equal to ("-32.768") - 

TestFoundation/TestNSNumber.swift:1155: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("32767") is not equal to ("32.767") - 

TestFoundation/TestNSNumber.swift:1156: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-2147483648") is not equal to ("-2.147.483.648") - 

TestFoundation/TestNSNumber.swift:1157: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("2147483647") is not equal to ("2.147.483.647") - 

TestFoundation/TestNSNumber.swift:1158: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("-9223372036854775808") is not equal to ("-9.223.372.036.854.775.808") - 

TestFoundation/TestNSNumber.swift:1159: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("9223372036854775807") is not equal to ("9.223.372.036.854.775.807") - 

TestFoundation/TestNSNumber.swift:1164: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("65535") is not equal to ("65.535") - 

TestFoundation/TestNSNumber.swift:1166: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("4294967295") is not equal to ("4.294.967.295") - 

TestFoundation/TestNSNumber.swift:1174: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1e+09") is not equal to ("1E+09") - 

TestFoundation/TestNSNumber.swift:1178: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 

TestFoundation/TestNSNumber.swift:1179: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1,175494e-38") is not equal to ("1,175494E-38") - 

TestFoundation/TestNSNumber.swift:1180: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1,401298e-45") is not equal to ("1,401298E-45") - 

TestFoundation/TestNSNumber.swift:1181: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("3,402823e+38") is not equal to ("3,402823E+38") - 

TestFoundation/TestNSNumber.swift:1184: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("1000000000") is not equal to ("1.000.000.000") - 

TestFoundation/TestNSNumber.swift:1187: error: TestNSNumber.test_descriptionWithLocale : XCTAssertEqual failed: ("nan") is not equal to ("NaN") - 

Test Case 'TestNSNumber.test_descriptionWithLocale' failed (0.008 seconds)

Also this is failing

Test Case 'TestNSString.test_initializeWithFormat3' started at 2019-02-23 13:16:26.238
TestFoundation/TestNSString.swift:838: error: TestNSString.test_initializeWithFormat3 : XCTAssertEqual failed: ("en_GB value is 1000 (42.0)") is not equal to ("en_GB value is 1,000 (42.0)") - 
TestFoundation/TestNSString.swift:844: error: TestNSString.test_initializeWithFormat3 : XCTAssertEqual failed: ("de_DE value is 1000 (42,0)") is not equal to ("de_DE value is 1.000 (42,0)") - 
Test Case 'TestNSString.test_initializeWithFormat3' failed (0.001 seconds)

[futurejones]

Build on master with PR #1866 is running now.

[futurejones]

All tests are passing on the master 😃 with PR #1866

--- Running tests for foundation ---
--- test ---
+ /usr/local/bin/cmake --build /home/worksonarm_test/jenkins_slave/workspace/swift-master-aarch64-test/build/buildbot_linux/foundation-linux-aarch64 -- -j96 test
[0/1][  0%][0.000s] Running tests...
Test project /home/worksonarm_test/jenkins_slave/workspace/swift-master-aarch64-test/build/buildbot_linux/foundation-linux-aarch64
    Start 1: TestFoundation
1/1 Test #​1: TestFoundation ...................   Passed   45.67 sec

100% tests passed, 0 tests failed out of 1

Total Test time (real) =  45.68 sec
-- test finished --
--- Finished tests for foundation ---

[spevans]

What about the swift-5.0-branch with that PR? I dont think there should be any differences between 5.0 and master wrt this change.

[futurejones]

Tested swift-5.0-branch with PR #1866 and 'TestNSNumber.test_descriptionWithLocale' and 'TestNSString.test_initializeWithFormat3' are still failing.

[spevans]

There isnt any difference between master and 5.0 for this code change so Im not sure why it is failing.

What build command are you using? Is it using the same build command for both?

That PR just checks ICU is a minimum version, which it satisfies.

[futurejones]

Both builds are identical clean builds using the [preset: buildbot_linux]
I will try another fresh build tomorrow.

[futurejones]

I have run foundation tests on new clean builds 2019-02-25 and the results are as follows:-

swift-4.2-branch

• 'TestNSNumber.test_descriptionWithLocale' and 'TestNSString.test_initializeWithFormat3' are now failing.

swift-5.0-branch - with PR #1866

• 'TestNSNumber.test_descriptionWithLocale' and 'TestNSString.test_initializeWithFormat3' are still failing.

master - with PR #1866

• 'TestNSNumber.test_descriptionWithLocale' and 'TestNSString.test_initializeWithFormat3' all tests passing.

[spevans]

I think this may actually be a Locale issue since it seems all of the failing tests have the decimalSeparator and groupingSeparator missing for en_GB and de_DE.

Could you try running the following test against all three versions, for comparison this is what I see on x86_64 Ubuntu18.04:

$ cat locale.swift
import Foundation

print("current locale:", Locale.current.identifier)
print("decimalSeparator:", Locale.current.decimalSeparator ?? "nil")
print("groupingSeparator:", Locale.current.groupingSeparator ?? "nil")
print(String(format: "%d", locale: Locale.current, 123456))
print(String(format: "%0.7g\n", locale: Locale.current, 1234.5678))

let en = Locale(identifier: "en_GB")
print("EN locale:", en.identifier)
print("EN decimalSeparator:", en.decimalSeparator ?? "nil")
print("EN groupingSeparator:", en.groupingSeparator ?? "nil")
print(String(format: "%d", locale: en, 123456))
print(String(format: "%0.7g\n", locale: en, 1234.5678))

let de = Locale(identifier: "de_DE")
print("DE locale:", de.identifier)
print("DE decimalSeparator:", de.decimalSeparator ?? "nil")
print("DE groupingSeparator:", de.groupingSeparator ?? "nil")
print(String(format: "%d", locale: de, 123456))
print(String(format: "%0.7g\n", locale: de, 1234.5678))
$ ~/swift-4.2.2-RELEASE-ubuntu18.04/usr/bin/swift locale.swift
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123456
1234.568

EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123456
1234.568

DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123456
1234,568

$ ~/swift-5.0-DEVELOPMENT-SNAPSHOT-2019-02-19-a-ubuntu18.04/usr/bin/swift locale.swift
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123,456
1,234.568

EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123,456
1,234.568

DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123.456
1.234,568

$ ~/swift-DEVELOPMENT-SNAPSHOT-2019-02-19-a-ubuntu18.04/usr/bin/swift locale.swift
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123,456
1,234.568

EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123,456
1,234.568

DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123.456
1.234,568

Here, 4.2.2 doesn't use the Locale for some reason but 5.0 and master both match

[futurejones]

[UPDATED]I am not seeing the same results on Ubuntu 16.04 AArch64
5.0 and master are different.

neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-4.2-aarch64-RELEASE/install/usr/bin/swift locale.swift 
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123456
1234.568


EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123456
1234.568


DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123456
1234,568


neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64-test/install/usr/bin/swift locale.swift 
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123456
1234.568


EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123456
1234.568


DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123456
1234,568


neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-master-aarch64/install/usr/bin/swift locale.swift 
current locale: en_US
decimalSeparator: .
groupingSeparator: ,
123,456
1,234.568


EN locale: en_GB
EN decimalSeparator: .
EN groupingSeparator: ,
123,456
1,234.568


DE locale: de_DE
DE decimalSeparator: ,
DE groupingSeparator: .
123.456
1.234,568

[spevans]

What happens if you run

import Foundation

let en = Locale(identifier: "en_GB")
print(String(format: "%d", locale: en, 123456))
print(String(format: "%0.7g\n", locale: en, 1234.5678))

let de = Locale(identifier: "de_DE")
print(String(format: "%d", locale: de, 123456))
print(String(format: "%0.7g\n", locale: de, 1234.5678)) 

since that is the function used by the .description(withLocale:)

[futurejones]

Here are the results -
swift-5.0-aarch64-test = patched with PR #1866
swift-5.0-aarch64 = no patch

neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-4.2-aarch64-RELEASE/install/usr/bin/swift locale2.swift 
123456
1234.568

123456
1234,568

neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64-test/install/usr/bin/swift locale2.swift 
123456
1234.568

123456
1234,568

neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-master-aarch64/install/usr/bin/swift locale2.swift 
123,456
1,234.568

123.456
1.234,568

neil@swiftyarm:~$ /home/worksonarm_test/jenkins_slave/workspace/swift-5.0-aarch64/install/usr/bin/swift locale2.swift 
123456
1234.568

123456
1234,568