[LLD] [MinGW] Expand comment for MinGW driver.

[mstorsjo]

Summary

Expand comment for MinGW driver.

[ruiu]

• fix typos

[smeenai]

lld/MinGW/Driver.cpp

10 ↗

(On Diff #168832)

Should be either "consists of" or "comes with"

16 ↗

(On Diff #168832)

differnet -> different

18 ↗

(On Diff #168832)

translate -> translates

21 ↗

(On Diff #168832)

calls lld/COFF driver -> calls the lld/COFF driver?

22 ↗

(On Diff #168832)

run lld/COFF linker -> run the lld/COFF linker?

26 ↗

(On Diff #168832)

implemented -> implements?

[mstorsjo]

+1 to the rest of @smeenai's comments

lld/MinGW/Driver.cpp

26 ↗

(On Diff #168832)

I don't see anything wrong with what's written here at the moment.

[smeenai]

lld/MinGW/Driver.cpp

26 ↗

(On Diff #168832)

It sounds more natural in the present tense to me (it flows better from the previous part of the sentence), but yeah, it's fine either way.

[mstorsjo]

@ruiu Do you have time to finish this one, there shouldn't be much to do?

[mstorsjo]

Corrected @smeenai's review comments.

[ruiu]

LGTM

Feel free to commit.

MinGW/Driver.cpp

 //===- MinGW/Driver.cpp ---------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-///
-/// GNU ld style linker driver for COFF currently supporting mingw-w64.
-///
+//
+// MinGW is a GNU development environment for Windows. It consists of GNU
+// tools such as GCC and GNU ld. Unlike Cygwin, there's no POSIX-compatible
+// layer, as it aims to be a native development toolchain.
+//
+// lld/MinGW is a drop-in replacement for GNU ld/MinGW.
+//
+// Being a native development tool, a MinGW linker is not very different from
+// Microsoft link.exe, so a MinGW linker can be implemented as a thin wrapper
+// for lld/COFF. This driver takes Unix-ish command line options, translates
+// them to Windows-ish ones, and then passes them to lld/COFF.
+//
+// When this driver calls the lld/COFF driver, it passes a hidden option
+// "-lldmingw" along with other user-supplied options, to run the lld/COFF
+// linker in "MinGW mode".
+//
+// There are subtle differences between MS link.exe and GNU ld/MinGW, and GNU
+// ld/MinGW implements a few GNU-specific features. Such features are directly
+// implemented in lld/COFF and enabled only when the linker is running in MinGW
+// mode.
+//
 //===----------------------------------------------------------------------===//
 
 #include "lld/Common/Driver.h"
 #include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"