[llvm-ar] Support verbose mode for operation 'x'

[jhenderson]

Code change looks good, but I've got a concern about the testing. (requesting changes to cancel approval)

llvm/test/tools/llvm-ar/extract.test

8

You need test cases for extracting without 'v', to show the behaviour in that case. With this change, 'x' alone is untested.

[MaskRay]

Add a non-'v' test

[jhenderson]

LGTM.

llvm/test/tools/llvm-ar/extract.test

 ## Test extract operation.
 # XFAIL: system-darwin
 
 RUN: rm -rf %t && mkdir -p %t/extracted/
 
 # Extracting from an empty archive should not warn or error:
 RUN: llvm-ar cr %t/empty.a
-RUN: llvm-ar x %t/empty.a 2>&1 | count 0
+RUN: llvm-ar xv %t/empty.a 2>&1 | count 0
 
 RUN: echo filea > %t/a.txt
 RUN: echo fileb > %t/b.txt
 RUN: llvm-ar rc %t/archive.a %t/a.txt %t/b.txt
 
 # Single member:
-RUN: cd %t/extracted && llvm-ar x %t/archive.a a.txt
+RUN: cd %t/extracted && llvm-ar xv %t/archive.a a.txt | FileCheck %s --check-prefix=A
 RUN: diff %t/a.txt %t/extracted/a.txt 
+A: x - a.txt
 
 # All members:
 RUN: rm %t/extracted/a.txt
-RUN: cd %t/extracted && llvm-ar x %t/archive.a
-RUN: diff %t/a.txt %t/extracted/a.txt 
-RUN: diff %t/b.txt %t/extracted/b.txt 
+RUN: cd %t/extracted && llvm-ar xv %t/archive.a | FileCheck %s --check-prefix=AB
+RUN: diff %t/a.txt %t/extracted/a.txt 
+RUN: diff %t/b.txt %t/extracted/b.txt 
+AB: x - a.txt
+AB: x - b.txt
+
+# No output if 'v' is not specified.
+RUN: rm a.txt b.txt
+RUN: llvm-ar x %t/archive.a 2>&1 | count 0
+RUN: diff %t/a.txt %t/extracted/a.txt
+RUN: diff %t/b.txt %t/extracted/b.txt

llvm/tools/llvm-ar/llvm-ar.cpp

 // Implement the 'x' operation. This function extracts files back to the file
 // system.
 static void doExtract(StringRef Name, const object::Archive::Child &C) {
   // Retain the original mode.
   Expected<sys::fs::perms> ModeOrErr = C.getAccessMode();
   failIfError(ModeOrErr.takeError());
   sys::fs::perms Mode = ModeOrErr.get();
 
+  llvm::StringRef outputFilePath = sys::path::filename(Name);
+  if (Verbose)
+    outs() << "x - " << outputFilePath << '\n';
+
   int FD;
-  failIfError(sys::fs::openFileForWrite(sys::path::filename(Name), FD,
+  failIfError(sys::fs::openFileForWrite(outputFilePath, FD,
                                         sys::fs::CD_CreateAlways,
                                         sys::fs::OF_None, Mode),
               Name);
 
   {
     raw_fd_ostream file(FD, false);
 
     // Get the data and its length