974060 - Error out when accessing non-existing keys from sandbox dictionary variables

Status: NEW

(Firefox Build System :: General, defect)

Description

[(no longer active)]

Using CONFIG['VARIABLE_WHICH_DOESNT_EXIST'] should fail the build.  See bug 973143 comment 13 for an example of what this can prevent.

Comment 1

[Gregory Szorc [:gps]]

The reason we don't do this is because not every variable is defined in every build configuration.

To fix this, we'll need to add missing AC_SUBST() to configure.in and support .m4 files.

A good first step would be to emit a warning when an unknown variable is accessed. We should be able to iteratively ratchet this down until it passed on automation. Even then, I fear we'll have a long-tail of one-offs in local configurations. Auditing 10,000+ lines of m4 ain't exactly my idea of fun.

Comment 2

[Gregory Szorc [:gps]]

A lesser reason is this matches the behavior of make.

Everyone agrees that in the ideal world configuration variables are well-defined. Nobody has wanted to invest the effort into fixing this.

Comment 3

[Mike Hommey [:glandium]]

AC_SUBST is unconditional. That is, something like this in configure.in:
  if foo; then
     AC_SUBST(bar)
  fi

*always* makes bar appear as a CONFIG variable.