stack build: Issues with flags

[harendra-kumar]

I wasted precious minutes trying to debug what's wrong when I made a mistake in defining and using a flag. The mistake I made was to put a ':' in the flag stanza of the cabal file, like this:

flag native:

When I ran stack build --flag unicode-transforms:native it just said:

These flags are used without having been defined: native

This is likely to be a cabal issue.

But what's strange is that with this mistake stack allows me to put any random name as a package name in stack.yaml flags section and on the command line flag spec without noticing anything wrong. E.g.

cueball:/vol/hosts/cueball/workspace/projects/unicode-transforms$ cat stack.yaml
flags:
    hahaha:
        native: true

extra-package-dbs: []
packages:
- '.'
extra-deps:
- data-list-sequences-0.1
resolver: lts-5.8

cueball:/vol/hosts/cueball/workspace/projects/unicode-transforms$ stack build --flag xxx:native 
These flags are used without having been defined: native

[mgsloan]

The stack part of this issue is fairly related to #1521

Looks like there is a check in the code but it may be broken:

stack/src/Stack/Build/Source.hs

Line 377 in 5f7ba82

checkFlagsUsed boptsCli lps extraDeps snapshot = do

[mgsloan]

Hmm, can no longer reproduce this:

mgsloan@computer:~/fpco/test-stack/issue1995/unicode-transforms$ stack build --flag hrrm:native
Invalid flag specification:
- Package 'hrrm' not found (specified on command line)
- Package 'hahaha' not found (specified in stack.yaml)

Closing!