IEEE Standards Interpretations for IEEE Std 1003.2™-1992 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)--Part 2: Shell and Utilities
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Interpretation Request #127
Topic: make Relevant Clauses: 18.104.22.168
Lines 322--323 state that "If make is invoked without any work needing to be done, it shall write a message to standard output indicating that no action was taken." My question is, what exactly is "no work needing to be done"? Historically, make would report that no worked needed to be done if there was no rule associated with either the dependency or with the inference rules, but would not report the lack of work if there was an empty rule (ie. a rule consisting only of whitespace). For example, the makefile .POSIX: foo: foo.u when executed with the command $ touch foo.u $ make foo would report that foo was up to date, since there is nothing to do, but the makefile .POSIX: foo: foo.u ; would complete silently, because there is something to do, namely "nothing".
The standard is unclear on this issue, and no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor.
Rationale for Interpretation