SrcSpan's associated with expanded quasi-quotes are inconsistent

Consider

{-# LANGUAGE TemplateHaskell #-}
module A where
import Language.Haskell.TH.Quote
qq = QuasiQuoter {
         quoteExp  = \str -> case str of
                                "a" -> [| True |]
                                "b" -> [| id True |]
                                "c" -> [| True || False |]
                                "d" -> [| False |]
       , quotePat  = undefined
       , quoteType = undefined
       , quoteDec  = undefined
       }


{-# LANGUAGE QuasiQuotes #-}
module B where
import A
ex1 = [qq|a|]
ex2 = [qq|b|]
ex3 = [qq|c|]
ex4 = [qq|d|]

In the expansion of [qq|a|] the source span for True is reported as 4:7-4:14 and 7:7-7:14 respectively -- i.e., the span of the entire quasi-quote. However, for the expansion of [qq|b|] and [qq|c|] the source span for id, True, False, and (||) are all reported as 5:11-5:14 / 6:11-6:14, i.e., starting at the "contents" of the quasi-quote.

Trac metadata

Trac field	Value
Version	7.4.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture