[llvm] [DirectX] Add `extract-section` to `llvm-objcopy` and implement it for `DXContainer` (PR #154804)

[James Henderson via llvm-commits]

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@@ -1082,6 +1082,14 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> ArgsArr,
           "bad format for --dump-section, expected section=file");
     Config.DumpSection.push_back(Value);
   }
+  for (auto *Arg : InputArgs.filtered(OBJCOPY_extract_section)) {
+    StringRef Value(Arg->getValue());
+    if (Value.split('=').second.empty())
+      return createStringError(
+          errc::invalid_argument,
+          "bad format for --extract-section, expected section=file");
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jh7370 wrote:

You need a test for this.

https://github.com/llvm/llvm-project/pull/154804