> As I wrote, the “bash” input above should be a *directory* containing
> exactly a sub-directory called ‘bin’, itself containing a static
> executable called ‘bash’.

I also copied 'bash' to 'sh'.  Because the build had failed without it.

After several hours, it failed again:

[...]

../../gcc-4.7.2/gcc/config/mips/gnu-user.h:94:309: warning: missing terminating " character [enabled by default]
../../gcc-4.7.2/gcc/config/mips/gnu-user.h:96:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user.h:97:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user.h:98:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user.h:99:36: warning: missing terminating " character [enabled by default]
../../gcc-4.7.2/gcc/config/mips/gnu-user.h:98:1: error: missing terminating " character
In file included from ./tm.h:36:0,
                 from ../../gcc-4.7.2/gcc/genflags.c:27:
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:31:309: warning: missing terminating " character [enabled by default]
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:33:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:34:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:35:1: error: expected identifier or '(' before '%' token
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:36:36: warning: missing terminating " character [enabled by default]
../../gcc-4.7.2/gcc/config/mips/gnu-user64.h:35:1: error: missing terminating " character
make[3]: *** [build/genflags.o] Error 1
make[3]: Leaving directory `/tmp/nix-build-4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv-0/build/gcc'
make[2]: *** [all-stage1-gcc] Error 2
make[2]: Leaving directory `/tmp/nix-build-4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv-0/build'
make[1]: *** [stage1-bubble] Error 2
make[1]: Leaving directory `/tmp/nix-build-4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv-0/build'
make: *** [all] Error 2
phase `build' failed after 2047 seconds
builder for `/nix/store/4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv' failed; keeping build directory `/tmp/nix-build-4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv-0'
builder for `/nix/store/4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv' failed with exit code 1
@ build-failed /nix/store/4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv /nix/store/n4blfp5bz6lvx9w9afn1i9c9v7akjnns-gcc-4.7.2 1 builder for `/nix/store/4i9pdi5wy5axlcp54g08f4f1gf82hlxx-gcc-4.7.2.drv' failed with exit code 1
cannot build derivation `/nix/store/v564vvxmyds190jlbxdmsxqnc5w35b6b-guile-2.0.7.drv': 1 dependencies couldn't be built
cannot build derivation `/nix/store/6cy3dcrbpblk73ch1knif3h09l5d1pbr-bootstrap-tarballs-0.drv': 1 dependencies couldn't be built
error: build failed: build of `/nix/store/6cy3dcrbpblk73ch1knif3h09l5d1pbr-bootstrap-tarballs-0.drv' failed

Should I ask GCC people about this error?

I can try to run 'strace' if you tell me what to look for.