gcc version is: i686-w64-mingw32-gcc.exe (GCC) 4.7.0 20111123 (experimental)
Platform is Mingw on Windows 7 HE SP1 64 bit, Athlon II X2 215
Building PostgreSQL from git tip (git clone git://github.com/postgres/postgres.git), configure --enable-cassert --enable-debug, then make && make check. This produces a regression failure in the PostgreSQL float8 test, specifically the error apparently occurs during a call to src/backend/utils/adt/float.c:float8mul(). It appears that there is some problem with isinf.
If CFLAGS=-O0 is set before configure, and the process is repeated, the error does not recur.
This code works on the same machine with gcc version "x86_64-w64-mingw32-gcc.exe (GCC) 4.5.3 20110401 (prerelease)"