Re: shortcut of ":" but not /bin/true

[Paul D. Smith]

%% David Boyce <address@hidden> writes:

  db> The ":" is given a third way which we might call the "blazing fast
  db> path"; it's not executed at all.

Right--along with the empty string :).

  db> Which raises the question: why wasn't the fast path in use in the
  db> truss output I showed? The answer is apparently that the generated
  db> Perl makefiles have an explicit SHELL=/bin/sh which disables the
  db> fast path.

Are you sure?  I'm surprised because there's some code in job.c which
checks the value of the SHELL variable to see whether it looks like a
valid shell; it basically does a strcmp() with "/bin/sh" and if it's
different it uses the slow path.

If this is broken we should definitely investigate.

Hm, I just ran a test and I don't think it invoked a shell:

    SHELL = /bin/sh
    all: ; @echo hi

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