[llvm] [llvm-ar] Use COFF archive format for COFF targets. (PR #82642)

[James Henderson via llvm-commits]

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@@ -969,12 +969,19 @@ Archive::Archive(MemoryBufferRef Source, Error &Err)
   Err = Error::success();
 }
 
+object::Archive::Kind Archive::getDefaultKindForTriple(Triple &T) {
+  if (T.isOSDarwin())
+    return object::Archive::K_DARWIN;
+  if (T.isOSAIX())
+    return object::Archive::K_AIXBIG;
+  if (T.isOSWindows())
+    return object::Archive::K_COFF;
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jh7370 wrote:

I'm a little nervous about how this impacts the default archive format on a Windows host: our downstream uses a cross-compiler, typically hosted on Windows, but using GNU-style archives (and the objects therefore have a different triple too).

I'm going to suggest to our internal binutils team that they run some testing with this patch applied, to see if it makes any difference.

https://github.com/llvm/llvm-project/pull/82642