> In context it should be clear that the statement  "in gcc 4.x it
> produces an error preventing build" refers to Cygwin's gcc and not
> MinGW's. Which gcc are you referring to?

If it refers to Cygwin only, sorry then. However, didn't folks said in 
MinGW thread that they didn't touch anything about such flag there? If 
so, then how can it have been removed later in 4.5 or 4.6 instead of 
4.0 like in Cygwin?

> Yes gcc 4.6 would fail because it won't accept the -mno-cygwin option.
> That does not mean that any other MinGW gcc ever *required* the
> -mno-cygwin option for anything.

Again, I was not saying it was required *for MinGW*, but *for building 
Pidgin*. Note that I'm not saying either that their use of such option 
was ever meaningful in the build process (in fact, they have removed 
such flag while still using 4.4, indicating that it was really useless).

> Yes but that particular error message is coming from Cygwin's gcc not
> MinGW. As stated by the Pidgin dev in that message the OP does not
> know which compiler they are using:
> http://pidgin.im/pipermail/support/2011-December/011159.html

We actually cannot confirm whether the GCC was from Cygwin, MSYS or Pidgin build box (the correct), and which version. It could be from Cygwin, but still my point stands, that the Pidgin developer does confirm that GCC 4.4 from MinGW *does* accept that flag.