some executables in the binary distribution are not versioned
GHC is generally quite careful to play nicely when you install multiple versions, in particular by putting a version number somewhere in the filepath for almost every installed file. Then a few top-level non-versioned symlinks are made to (versioned) executables. Consequently, build tools with enough knowledge of the GHC versioning infrastructure can select an older or newer GHC to build things with by ignoring the top-level symlinks and explicitly selecting the versioned executable names.
There are a few exceptions where this is not possible: hsc2hs, hp2ps, and hpc. These executables are *overwritten* on each installation, so it is not possible to select "the one that goes with the currently chosen compiler".
I'd like to request that these begin being installed with the same scheme as other GHC executables: with an appended dash and version number, together with a non-versioned symlink.
I don't know to what extent this matters for hp2ps and hpc; perhaps these change infrequently enough that it doesn't matter too much. But hsc2hs at least bakes some GHC version knowledge in; it has at least a default template that it #include's that defines some C macros, and this template changes occasionally. There is a command-line option to specify a template filepath explicitly, but it would be nice if build tools could reliably choose a version of hsc2hs that has the right defaults, so that using the command-line flag is a special case for special circumstances.
(For some context: I have just finished hunting down an issue related to exactly this. I installed an older GHC to test that some code was backwards-compatible. All of a sudden, existing builds, still using the new compiler, started failing, because hsc2hs was now using an outdated template that did not define all the necessary macros.)