The setting files.trimTrailingWhitespace does not seem to trim trailing whitespace when a file is saved. Is this a deliberate decision?

files.trimTrailingWhitespace format settings has the same behavior than other XML format settings, in other words format is done when you execute it (format document or range formatting). We use files.trimTrailingWhitespace to avoid creating a new settings like xml.format.trimTrailingWhitespace.

But I agree with you, it's strange because vscode description says that it execute this format on save:

Perhaps we should have the two formatting settings:

• xml.format.trimTrailingWhitespaceNoSave (trimTrailingWhitespace without save like today)
• files.trimTrailingWhitespace (trimTrailingWhitespace when it is saved)

@fbricon @xorye @datho7561 what do you think about that?

I think it makes sense to be consistent with other language servers/language support. I've checked TypeScript and Java files, and trailing white space is always removed by the formatter. Both these services also remove the trailing whitespace when files.trimTrailingWhitespace is set and the document is saved.

Thanks for the feedback. I agree with @datho7561 in that consistency with other languages will prevent user confusion. The main thing that caught me was that the setting (as shown in the screenshot @angelozerr highlighted) did not have an effect when saving files but VSCode indicated that it should.

I do not have an opinion on whether or not there is a separate setting to strip trailing whitespace only while formatting (since in my use case it will be stripped when I save anyway) but I am used to formatting stripping trailing spaces as part of the formatting process in the languages/file types I use.