For the sake of completeness, I thought I would update this again.
Turns out that the -fno-keep-inline-dllexport is necessary to get Qt to compile under MinGW's 4.6.2 g++ compiler. Evidently all of those inline dllexport function attribute definitions cause serious object bloat and cause the compiler to run out of memory. Here's a quote from the gcc docs (section 6.30 "Declaring Attributes of Functions"):
"In previous versions of GCC, the dllexport attribute was ignored for inlined functions, unless the -fkeep-inline-functions flag had been used. The default behaviour now is to emit all dllexported inline functions; however, this can cause object file-size bloat, in which case the old behaviour can be restored by using -fno-keep-inline-dllexport"
I find it interesting that the old compiler (4.4.5) does not cause the problem I experienced, but yet adding the option that is supposed to restore the old compiler's behavior for the new compiler (4.6.2) *does* cause the problem.
I was going to rebuild Qt (currently using 4.7.4) to take out the -fno-keep-inline-dllexport option, in case linking against Qt DLLs with that option might cause the same problem I had in my test program (which was *not* linked with Qt's DLLs). However, Qt won't compile successfully with g++ 4.6.2 from MinGW without that option.
I haven't yet tried to build an loadable library which is linked with Qt's DLLs against the Gambit library which was compiled without "-fno-keep-inline-dllexport". I kind of suspect that this scenario will work, since the problem seemed to be with Gambit's library being compiled that way. At the moment I'm building Qt *with* -fno-keep-inline-dllexport just to get it back the way it was. I'll try to report back later on what I discover about a Qt-linked loadable library.
I would be interested to know why the -fno-keep-inline-dllexport option causes a problem for Gambit. I'm sure I don't have enough understanding of the inter-workings of Gambit to figure it out myself, but I'd be willing to try to help as much as I can to help determine the cause.
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