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(Note that 7.10.1 works as expected)

This one line generates a panic:

panic = GarbageConstructorName $ a --$ b

(in an otherwise blank file, when passed to ghc or ghci. Just the right hand side panics ghci interactively.)

Error message:

ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.11.20150708 for x86_64-unknown-linux):
        get_op (--$)

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

uname -a: Linux cam-05-unx 3.5.0-54-generic #81~precise1-Ubuntu SMP Tue Jul 15 04:02:22 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

gcc -v:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)

With ghc -v (Was built with BuildFlavour = devel2, default build.mk otherwise):

Glasgow Haskell Compiler, Version 7.11.20150708, stage 2 booted by GHC version 7.8.2
Using binary package database: /5playpen/t-bepric/ghc-build/inplace/lib/package.conf.d/package.cache
wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace
wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace
wired-in package base mapped to base-4.8.2.0-inplace
wired-in package rts mapped to builtin_rts
wired-in package template-haskell mapped to template-haskell-2.10.0.0-inplace
wired-in package ghc mapped to ghc-7.11.20150708-inplace
wired-in package dph-seq not found.
wired-in package dph-par not found.
Hsc static flags: 
wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace
wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace
wired-in package base mapped to base-4.8.2.0-inplace
wired-in package rts mapped to builtin_rts
wired-in package template-haskell mapped to template-haskell-2.10.0.0-inplace
wired-in package ghc mapped to ghc-7.11.20150708-inplace
wired-in package dph-seq not found.
wired-in package dph-par not found.
*** Chasing dependencies:
Chasing modules from: *GetOpCrash.hs
Stable obj: []
Stable BCO: []
Ready for upsweep
  [NONREC
      ModSummary {
         ms_hs_date = 2015-07-08 15:09:13 UTC
         ms_mod = Main,
         ms_textual_imps = [import (implicit) Prelude]
         ms_srcimps = []
      }]
*** Deleting temp files:
Deleting: 
compile: input file GetOpCrash.hs
Created temporary directory: /tmp/ghc22576_0
*** Checking old interface for Main:
[1 of 1] Compiling Main             ( GetOpCrash.hs, GetOpCrash.o )
*** Parser:
*** Renamer/typechecker:
*** Deleting temp files:
Deleting: /tmp/ghc22576_0/ghc_1.s
Warning: deleting non-existent /tmp/ghc22576_0/ghc_1.s
*** Deleting temp dirs:
Deleting: /tmp/ghc22576_0
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.11.20150708 for x86_64-unknown-linux):
        get_op (--$)

Trac metadata

Trac field	Value
Version	7.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Linux
Architecture	x86_64 (amd64)