René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Start-Transcript uses lossy ASCII character encoding instead of BOM-less UTF-8 if the target file happens to exist","articleBody":"Note: \r\n * Windows PowerShell is _not_ affected - UTF-8 with BOM is used consistently there.\r\n * A fix for the closely related #13678 could probably encompass a fix for this issue as well.\r\n\r\nWhen the target file _happens to exist and doesn't have a BOM_ - even without `-Append` - `Start-Transcript` mistakenly uses ASCII encoding to write the file.\r\n\r\nWithout `-Append`, `Start-Transcript` shouldn't even look at the existing file - it should simply replace it, and use the default encoding (BOM-less UTF-8). See #13678 for a closely related bug _with_ `-Append`.\r\n\r\nInstead, `Start-Transcript` apparently looks for a BOM at the start of an existing file and uses ASCII encoding if it doesn't find one.\r\n\r\n## Steps to reproduce\r\n\r\n```powershell\r\n# To surface the bug, make sure that the target file exists and doesn't have a BOM.\r\n$null \u003e temp:/$PID.txt\r\n\r\n$null = Start-Transcript temp:/$PID.txt\r\n'ü' # output a string with a non-ASCII-range character\r\n$null = Stop-Transcript\r\n\r\nSelect-String -Quiet 'ü' temp:/$PID.txt | Should -BeTrue\r\n\r\nRemove-Item temp:/$PID.txt\r\n```\r\n\r\n## Expected behavior\r\n\r\nThe test should succeed.\r\n\r\n## Actual behavior\r\n\r\nThe test fails, because `ü` was transliterated to verbatim `?`, suggesting that ASCII encoding was used to write the file.\r\n\r\n## Environment data\r\n\r\n```none\r\nPowerShell Core 7.1.0-preview.7\r\n```\r\n","author":{"url":"https://github.com/mklement0","@type":"Person","name":"mklement0"},"datePublished":"2020-09-23T14:41:15.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":28},"url":"https://github.com/13677/PowerShell/issues/13677"}