Numeric only variable name in CMake

Question

What was the reason to allow numeric only variable names in CMake? It makes the next code frustrative (if's condition becomes true):

set(1 3)
set(2 3)
if (1 EQUAL 2)
    MESSAGE( "hi there" )
endif()

And even more likely usage (if's condition becomes true also):

set(1 2)
... # later on, or even in the other file:
set(var1 1)
if (${var1} EQUAL 2)
    MESSAGE( "hi there" )
endif()

PS I understand why variable references without ${} used inside IF/WHILE. But the possibility of numeric only variable names makes using IFs more error-prone...

The true reason is probably known to CMake developers only, so it is better to ask them directly. — Tsyvarev, Apr 02 '18 at 07:31
@Tsyvarev Not something I would have expected to be valid, although the docs do technically seem to allow it. — Craig Scott, Apr 02 '18 at 12:13
Please report this one in the CMake [bug tracker](https://gitlab.kitware.com/cmake/cmake/issues/new). — Craig Scott, Apr 02 '18 at 12:14
Thanks for the link @CraigScott Bug reported: https://gitlab.kitware.com/cmake/cmake/issues/17885 — Artsiom Chapialiou, Apr 06 '18 at 16:46
Things like this are why I always quote my literal arguments and use quote-wrapped explicit variable referencing in my `if()` commands. — starball, Apr 20 '23 at 21:11

score 0 · Answer 1 · answered Apr 08 '18 at 02:18

Answer from Brad King at CMake issue tracker:

For reference, variable names are arbitrary strings, e.g.

set(var "almost anything here")
set("${var}" value)
message(STATUS "${${var}}")

Allowing numeric-only names is a side effect of that.

Certainly they can be used in confusing ways. Disallowing them, even if only for if() evaluation, would require a policy.

Numeric only variable name in CMake

1 Answers1

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