bad lines ignored and no warning?

[Marc Weber]

Today I spend quite a while figuring out why I could install base<4
while using flag base4.
The reason was that I forgot to add the label build-depends: when
patching.
If those lines are ignored shouldn't there be a warning?

Marc Weber

name:QuickCheck
version:1.2.0.0
license:BSD3
license-file:LICENSE
author:Koen Classen and John Hughes
maintainer:libraries at haskell.org
category:Testing
homepage:http://www.math.chalmers.se/~rjmh/QuickCheck/
synopsis:Automatic testing of Haskell programs
description:
        A library for testing Haskell programs automatically.
        The programmer provides a specification of the program, in
        the form of properties which functions should satisfy, and
        QuickCheck then tests that the properties hold in a large number
        of randomly generated cases.  Specifications are expressed in
        Haskell, using combinators defined in the QuickCheck library.
        QuickCheck provides combinators to define properties, observe
        the distribution of test data, and define test
        data generators.
build-type: Simple
cabal-version: >=1.2

flag split-base
flag base4

library
  exposed-modules:
          Debug.QuickCheck.Batch,
          Debug.QuickCheck.Poly,
          Debug.QuickCheck.Utils,
          Debug.QuickCheck,
          Test.QuickCheck.Batch,
          Test.QuickCheck.Poly,
          Test.QuickCheck.Utils,
          Test.QuickCheck
  if flag(split-base)
    build-depends:base >= 3 && < 5, random
    if flag(base4)
      base >= 4
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <<
      cpp-options: -DBASE4
    else
      base < 4
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <<
  else
    build-depends:base < 3
  extensions:CPP