Macro causes segfault

[dawbarton]

I'm pretty sure the macro below doesn't do what I intended but I'm also pretty sure that it shouldn't cause a segfault...

julia> macro killme(expr)
       esc(:(global a))
       end
@killme (macro with 1 method)

julia> @killme 1+1

signal (11): Segmentation fault
in expression starting at no file:0
jl_array_ptr_ref at /buildworker/worker/package_linux64/build/src/julia.h:785 [inlined]
body_attributes at /buildworker/worker/package_linux64/build/src/toplevel.c:404 [inlined]
jl_toplevel_eval_flex at /buildworker/worker/package_linux64/build/src/toplevel.c:761
jl_toplevel_eval_in at /buildworker/worker/package_linux64/build/src/builtins.c:622
eval at ./boot.jl:319 [inlined]
#13 at /home/db9052/.julia/packages/Atom/jJn7Y/src/repl.jl:125 [inlined]
with_logstate at ./logging.jl:397
jl_fptr_trampoline at /buildworker/worker/package_linux64/build/src/gf.c:1829
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2182
with_logger at ./logging.jl:493
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2182
top-level scope at /home/db9052/.julia/packages/Atom/jJn7Y/src/repl.jl:124
jl_fptr_trampoline at /buildworker/worker/package_linux64/build/src/gf.c:1829
jl_toplevel_eval_flex at /buildworker/worker/package_linux64/build/src/toplevel.c:781
jl_toplevel_eval_in at /buildworker/worker/package_linux64/build/src/builtins.c:622
eval at ./boot.jl:319
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2182
eval_user_input at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.0/REPL/src/REPL.jl:85
macro expansion at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.0/REPL/src/REPL.jl:117 [inlined]
#28 at ./task.jl:259
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2182
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1536 [inlined]
start_task at /buildworker/worker/package_linux64/build/src/task.c:268
unknown function (ip: 0xffffffffffffffff)
Allocations: 18071712 (Pool: 18068443; Big: 3269); GC: 40

Version info is

Julia Version 1.0.0
Commit 5d4eaca0c9 (2018-08-08 20:58 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, broadwell)
Environment:
  JULIA_EDITOR = atom
  JULIA_NUM_THREADS = 2

Thanks.

[ararslan]

Behavior in Julia 0.6:

$ julia-0.6 -e 'macro killme(ex) esc(:(global a)) end; @killme 1+1'
ERROR: syntax: misplaced "global" declaration

[ararslan]

As a debugging breadcrumb, running with a debug build produces this:

julia> macro killme(ex)
           esc(:(global a))
       end
@killme (macro with 1 method)

julia> @killme 1+1
julia: /data/ararslan/julia/src/toplevel.c:762: jl_toplevel_eval_flex: Assertion `head == thunk_sym' failed.

[Keno]

This one's for @JeffBezanson probably, but he's on vacation until the end of next week (though he may get bored before then).

[JeffBezanson]

Fixed by #28882