On Mon, 5 Sep 2022 19:00:56 GMT, Magnus Ihse Bursie <i...@openjdk.org> wrote:
>>> I think you really mean `$$($1_SRCS)` here, since the vardeps file is a >>> build internal file that javac do not and should not care about. While I'm >>> sure it will ignore it, the code here will be clearer if we don't pass it >>> around when we shouldn't. >> >> Hm, but `$$($1_SRCS)` contains all the source files of the given module, >> modified and unmodified, correct? The point of this patch is that we send >> the list of modified files to the `Depend` plugin (all sources are still >> passed to the javac invocation), and the plugin decides whether or not all >> files should be compiled, or only the modified files should be compiled. >> >> The plugin could theoretically do the timestamp check from the sources, but >> it is more difficult to do, and the make has (presumably) already done that >> in a predictable way. >> >> The `Depend` plugin will do a full build if a non-Java file is present in >> the list, which I hope should lead to a more reliable recompilation for some >> complex changes among the sources. >> >> Note that the modfiles are not sent to javac as such - all sources are still >> sent to javac. The modfiles are sent to the `Depend` plugin using a side >> channel. > > Right, I confused `$?` and `$+`. You are of course correct, this is the way > to get the changed targets. I had a bit of bad luck when I though about this. > 😄 (Theoretically, we could filter out anything that is not in `$1_SRCS` from > `$?` but that seems to more work than is reasonable.) > The `Depend` plugin will do a full build if a non-Java file is present in the > list, which I hope should lead to a more reliable recompilation for some > complex changes among the sources. Ah, I had missed that and that's clever! That also means there is a reason to generate MODFILES in the actual compile recipe instead of the separate rule as I suggested earlier. For this to be "safe" we need `$$?` to really contain all the updated prereqs, otherwise we may miss compiling everything when something external actually should make us do just that. ------------- PR: https://git.openjdk.org/jdk/pull/10104
