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fix: remove preceding -Xcc instead of the argument following -Werror or -Wwarning #9194

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fix: remove preceding -Xcc instead of the argument following -Werror or -Wwarning #9194

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3168b15
fix: remove preceding `-Xcc` instead of the argument following `-Werr…
Sep 26, 2025
91f2587
refactor: use simple for loop instead of filter with side-effect closure
Sep 29, 2025
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23 changes: 9 additions & 14 deletions Sources/Build/BuildDescription/SwiftModuleBuildDescription.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -611,26 +611,21 @@ public final class SwiftModuleBuildDescription {
// suppress warnings if the package is remote
if self.package.isRemote {
// suppress-warnings and the other warning control flags are mutually exclusive
var removeNextArg = false
args = args.filter { arg in
if removeNextArg {
removeNextArg = false
return false
}
var filteredArgs = [String]()
for arg in args {
switch arg {
case "-warnings-as-errors", "-no-warnings-as-errors":
return false
// Skip this flag
continue
case "-Wwarning", "-Werror":
removeNextArg = true
return false
// Remove preceding -Xcc and skip this flag
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Rereading this code again, I think this was actually intended to filter out -Werror SwiftWarningGroup (which is also valid) rather than -Xcc -Werror. I think you'll need to examine the preceding arg to check if it's actually -Xcc and therefore safe to remove. If the arg is passed to swiftc directly, the following arg should probably continue to be removed. It would be nice to have some tests for this as well.

Stepping back, this makes me think the compiler should stop diagnosing conflicting flags here and just allow one to win

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@loonatick-src loonatick-src Sep 30, 2025 •
edited
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I think this was actually intended to filter out -Werror SwiftWarningGroup

Ah, I did not know that. Just found -Werror in swiftc --help-hidden.

So, if I understand correctly, the following cases can happen.

  • -Xcc -Werror
  • -Xcc -Werror=<CppWarningGroup>
  • -Werror <SwiftWarningGroup>

and the corresponding Wwarning variants. Anything missing?

Edit: I suppose the complete list is in this proposal.

For C/C++:

  • -Wxxxx
  • -Wno-xxxx
  • -Werror
  • -Werror=xxxx
  • -Wno-error
  • -Wno-error=xxxx

For Swift:

  • -warnings-as-errors
  • -no-warnings-as-errors
  • -Wwarning xxxx
  • -Werror xxxx

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@loonatick-src loonatick-src Sep 30, 2025 •
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the compiler should stop diagnosing conflicting flags here and just allow one to win

@owenv If that would be the case, then -suppress-warnings would have to win out over the others for remote packages. But that might not be a good default for non-remote packages.

filteredArgs.removeLast()
default:
return true
filteredArgs.append(arg)
}
}
guard !removeNextArg else {
throw InternalError("Unexpected '-Wwarning' or '-Werror' at the end of args")
}
args += ["-suppress-warnings"]
args = filteredArgs
args.append("-suppress-warnings")
}

// Pass `-user-module-version` for versioned packages that aren't pre-releases.
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