> offers you virtually no help in writing correct parallel and incremental builds.
The key problem there that Make has no idea about the semantics of the shell code that appears in the build recipes. It has no idea how two build recipes interact with each other through side effects on objects that are not listed as targets or prerequisites.
I think ClearCase's clearmake (GNU-compatible) actually intercepts the file system calls (because the build happens on a ClearCase mounted VOB). So it is able to infer the real inputs and outputs of a build recipe at run-time. For instance, it would know that "yacc foogrammar.y" produced a "y.tab.h" even if the rules make no mention of this. So in principle it's possible to know that one rule is consuming "y.tab.h" (opens it for reading), that is produced by another rule (that wrote it), without there being any dependency tied to this data flow.
The interception could be done by injecting shared lib wrappers, I suppose. Our friend LD_PRELOAD and all that.
Of course, if we fix the parallel build with proper dependencies, a fixed incremental build also pops out of that.
The key problem there that Make has no idea about the semantics of the shell code that appears in the build recipes. It has no idea how two build recipes interact with each other through side effects on objects that are not listed as targets or prerequisites.
I think ClearCase's clearmake (GNU-compatible) actually intercepts the file system calls (because the build happens on a ClearCase mounted VOB). So it is able to infer the real inputs and outputs of a build recipe at run-time. For instance, it would know that "yacc foogrammar.y" produced a "y.tab.h" even if the rules make no mention of this. So in principle it's possible to know that one rule is consuming "y.tab.h" (opens it for reading), that is produced by another rule (that wrote it), without there being any dependency tied to this data flow.
The interception could be done by injecting shared lib wrappers, I suppose. Our friend LD_PRELOAD and all that.
Of course, if we fix the parallel build with proper dependencies, a fixed incremental build also pops out of that.