[llvm-lib] Support adding short import library objects with llvm-lib

This fixes PR 42837.

Differential Revision: https://reviews.llvm.org/D84465

llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp

@@ -191,9 +191,11 @@ static void appendFile(std::vector<NewArchiveMember> &Members,
   file_magic Magic = identify_magic(MB.getBuffer());
 
   if (Magic != file_magic::coff_object && Magic != file_magic::bitcode &&
-      Magic != file_magic::archive && Magic != file_magic::windows_resource) {
+      Magic != file_magic::archive && Magic != file_magic::windows_resource &&
+      Magic != file_magic::coff_import_library) {
     llvm::errs() << MB.getBufferIdentifier()
-                 << ": not a COFF object, bitcode, archive or resource file\n";
+                 << ": not a COFF object, bitcode, archive, import library or "
+                    "resource file\n";
     exit(1);
   }
 

llvm/test/tools/llvm-lib/implibs.test

@@ -0,0 +1,12 @@
+Test that import libraries (and the members thereof) can be added to another
+static library.
+
+RUN: rm -rf %t
+RUN: mkdir -p %t
+
+RUN: echo -e "EXPORTS\nMyFunc" > %t/lib.def
+RUN: llvm-dlltool -m i386:x86-64 -l %t/lib.lib -d %t/lib.def -D lib.dll
+RUN: llvm-lib -out:%t/newlib.lib %t/lib.lib
+
+RUN: llvm-ar t %t/newlib.lib | FileCheck %s
+CHECK: lib.dll

llvm/test/tools/llvm-lib/invalid.test

@@ -1,2 +1,2 @@
 RUN: not llvm-lib %S/Inputs/cl-gl.obj 2>&1 | FileCheck %s
-CHECK: not a COFF object, bitcode, archive or resource file
+CHECK: not a COFF object, bitcode, archive, import library or resource file