VCC will not parse a literal negative number where INT is expected

[slimhazard]

Expected Behavior

VCC should parse a literal negative number such as -10 where an INT is expected.

The C typedef for VCL_INT is (signed) long, so it's not a problem with the data type, just the parser.

Current Behavior

When VCC sees -, it emits this error message and fails the parse:

Message from VCC-compiler: Unknown token '-' when looking for INT

Both of these workarounds will get a negative value into the INT:

std.integer("-10", 0)
0 - 1   # i.e. 1 subtracted from 0

std.integer("-10", -10) doesn't work, because INT is specified for the fallback parameter, so the same error is raised.

Possible Solution

If I'm reading the VCC code right, it looks like the CNUM type will have to permit the expression to begin with -. And it that case the conversion will have to negate the result of vcc_UintVal(), which currently returns unsigned (and the comments say that it expects digits only).

Steps to Reproduce (for bugs)

Use a negative literal in VCL at any position where INT is expected.

Context

VMOD development, but this is a general VCL issue.

Your Environment

Varnish trunk (but the problem has presumably always been there)

[gquintard]

One slightly less annoying way of doing it is to trick the parser with a substraction:

std.integer("-10", 0-10)