URL:
<http://savannah.gnu.org/bugs/?40159>
Summary: Premature exit with incorrect error message, or
garbage output characters.
Project: make
Submitted by: padavo
Submitted on: Wed 02 Oct 2013 05:39:01 PM GMT
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: 3.81
Operating System: POSIX-Based
Fixed Release: None
Triage Status: None
_______________________________________________________
Details:
I am seeing a bug with the Gnu Make parsing under certain conditions. It
behaves like runtime corruption of internal data structures that is rarely
triggered.
On debian 7:
$ dpkg -s make
Architecture: i386
Version: 3.81-8.2
Here is a complete minimal example makefile that I hope will demonstrate it.
If the long foreach lines have been line-wrapped by this web interface, please
restore them to a single line each as indicated by their newline escapes.
--------------------------------------
.PHONY: dummy
dummy:
# lazy evaluation, refer Mecklenburg "GNU Make" 3ed p189-190
define lazy
$1 = $$($1_lazy) $$($1)
$1_lazy = $$(eval $1 := $2)
endef
define def
$(eval $(call lazy,ooo,i))
$(warning $(ooo))
endef
$(foreach x,X X X X X X X X ,\
$(foreach y,Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Y Y Y Y ,\
$(eval $(call def,A,B))))
--------------------------------------
Running 'make -R -r' with the above makefile gives
Makefile:15: i
(repeated 100 times followed by)
Makefile:15: *** unterminated variable reference. Stop.
It does not complete all of the foreach expansions, and exits with status=2.
The purpose of the strange foreach arguments is to stimulate this bug to
appear both in bash and under gdb. If these are shortened, the bug does not
appear.
More evidence that bad things are happening internally can be seen by
trivially changing the variable name from 'ooo' to 'oo', ie two lines are
changed as follows:
define def
$(eval $(call lazy,oo,y))
$(warning $(oo))
endef
Running with this change, the above error does not occur! The foreach
completes, and all the strings printed by $(warning $(oo)) include 'i'
character as expected.
However several long groups of them have an extra garbage character after the
'i', such as byte 18hex (ASCII cancel character). So something bad is
happening there still, even though the exit status is zero.
I also observe that all these symptoms might disappear depending on other
apparently random factors such as what files might be present in the current
directory, editing comments in the makefile, or running under gdb.
Also this bug likes to hide, it took several hours of trial and error for me
to produce this minimal example which consistently demonstrates it in an empty
directory. Small edits to the example are likely to make the bug disappear. I
hope it actually occurs on your machine. I tested this on two different
hardware.
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