Follow-up Comment #4, bug #13529 (project make):
I'm experiencing similar problems with V3.81. The symptoms are these:
1. make clean
2. make -- make rebuilds everything, with no warnings about circular
dependencies.
3. make -- nothing to do, but I get hundreds of false warnings about circular
dependencies.
I decided to debug the issue. There is a bug in the following two functions
of remake.c:
+ update_file_1
+ check_deps
At the top of remake.c, there are three macros:
+ start_updating(file)
+ end_updating(file)
+ is_updating(file)
These macros set, clear, and test the 'updating' flag in the 'struct file*'
object passed.
The functions recursively traverse the dependency tree for a given target.
These functions set the 'updating' flag on the 'struct file*' argument
shortly after entry, and clear the 'updating' flag before exiting. A
circular dependency is detected when 'is_updating(file)' is true on entry to
either of these functions. In a true circular dependency the traversal would
loop back onto itself -- eventually -- and the 'updating' flag would be set.
The assumption in the above functions is that they are setting and clearing
the 'updating' flag on the same 'struct file*' object. Unfortunately that
assumption is false. In the presence of 'vpath' definitions, they often set
the 'updating' flag on one 'struct file*' object, but clear it on a different
one. These leaves 'struct file*' objects floating around with an 'updating'
flag that is set, but never cleared. Later when these functions are
traversing the dependencies of the next target, they run across a 'struct
file*' object with the 'updating' flag set, and incorrectly report a circular
dependency error.
To validate this I modified the above macros to dump information about which
object they were working with. This resulted in the following:
01 ....BEG update: (1) ual.a (0x905a1c8)
02 .....BEG update: (1) ual.a (0x905a1c8)
03 ......BEG update: (1) ual.a(File.o) (0x9059728)
04 .......BEG update: (1) ual.a(File.o) (0x9059728)
05 ........BEG update: (1) File.o (0x9056c40)
06 .........BEG update: (1) File.cpp (0x905a308)
07 ..........BEG update: (1) File.cpp (0x905a308)
08 ..........END update: (0) File.cpp (0x905a308)
09 .........END update: (0) ../File.cpp (0x905a308)
10 .........BEG update: (1) .dfiles/.mkdir (0x905b040)
11 ..........BEG update: (1) .dfiles/.mkdir (0x905b040)
12 ..........END update: (0) .dfiles/.mkdir (0x905b040)
13 .........END update: (0) .dfiles/.mkdir (0x905b040)
14 .........BEG update: (1) ../File.cpp (0x905a308)
15 .........END update: (0) ../File.cpp (0x905a308)
16 .........BEG update: (1) ual/File.h (0x9049448)
17 ..........BEG update: (1) ual/File.h (0x9049448)
18 ...........BEG update: (1) File.h (0x905b120)
19 ............BEG update: (1) File.h (0x905b120)
20 ............END update: (0) File.h (0x905b120)
21 ...........END update: (0) ../File.h (0x905b120)
22 ...........BEG update: (1) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
23 ............BEG update: (1) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
24 ............END update: (0) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
25 ...........END update: (0) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
26 ..........END update: (0) ../../x86-linux-fedora-4/include/ual/File.h
(0x9058ef0)
27 .........END update: (0) ../../x86-linux-fedora-4/include/ual/File.h
(0x9058ef0)
28 .........BEG update: (1) ual/FileNotFoundException.h (0x905f3f0)
29 ..........BEG update: (1) ual/FileNotFoundException.h (0x905f3f0)
30 ...........BEG update: (1) FileNotFoundException.h (0x905b280)
31 ............BEG update: (1) FileNotFoundException.h (0x905b280)
32 ............END update: (0) FileNotFoundException.h (0x905b280)
33 ...........END update: (0) ../FileNotFoundException.h (0x905b280)
34 ...........BEG update: (1) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
35 ...........END update: (0) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
36 ..........END update: (0)
../../x86-linux-fedora-4/include/ual/FileNotFoundException.h (0x9058f98)
37 .........END update: (0)
../../x86-linux-fedora-4/include/ual/FileNotFoundException.h (0x9058f98)
38 ........END update: (0) File.o (0x9056c40)
39 .......END update: (0) ual.a(File.o) (0x9059728)
40 ......END update: (0) ual.a(File.o) (0x9059728)
41 ......BEG update: (1) ual.a(FileNotFoundException.o) (0x9059780)
42 .......BEG update: (1) ual.a(FileNotFoundException.o) (0x9059780)
43 ........BEG update: (1) FileNotFoundException.o (0x9056da0)
44 .........BEG update: (1) FileNotFoundException.cpp (0x905ec00)
45 ..........BEG update: (1) FileNotFoundException.cpp (0x905ec00)
46 ..........END update: (0) FileNotFoundException.cpp (0x905ec00)
47 .........END update: (0) ../FileNotFoundException.cpp (0x905ec00)
48 .........BEG update: (1) .dfiles/.mkdir (0x905b040)
49 .........END update: (0) .dfiles/.mkdir (0x905b040)
50 .........BEG update: (1) ../FileNotFoundException.cpp (0x905ec00)
51 .........END update: (0) ../FileNotFoundException.cpp (0x905ec00)
52 make[2]: Circular FileNotFoundException.o <- ual/File.h dependency
dropped.
53 make[2]: Circular FileNotFoundException.o <- ual/FileNotFoundException.h
dependency dropped.
54 ........END update: (0) FileNotFoundException.o (0x9056da0)
55 .......END update: (0) ual.a(FileNotFoundException.o) (0x9059780)
56 ......END update: (0) ual.a(FileNotFoundException.o) (0x9059780)
In the above, I'm building a library (ual.a), using the archive member rules.
Of particular interest in the above are the following lines:
16 .........BEG update: (1) ual/File.h (0x9049448)
17 ..........BEG update: (1) ual/File.h (0x9049448)
18 ...........BEG update: (1) File.h (0x905b120)
19 ............BEG update: (1) File.h (0x905b120)
20 ............END update: (0) File.h (0x905b120)
21 ...........END update: (0) ../File.h (0x905b120)
22 ...........BEG update: (1) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
23 ............BEG update: (1) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
24 ............END update: (0) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
25 ...........END update: (0) ../../x86-linux-fedora-4/include/ual/.mkdir
(0x9049748)
26 ..........END update: (0) ../../x86-linux-fedora-4/include/ual/File.h
(0x9058ef0)
27 .........END update: (0) ../../x86-linux-fedora-4/include/ual/File.h
(0x9058ef0)
The above is produced by the 'start_updating' and 'finish_updating' macros.
The level, file name, and object address are printed. The 'updating' flag
value is also printed. Each matching BEG/END represents the enter/exit from
one of the above functions.
Note that at line 16 make is setting the 'updating' flag on 'ual/File.h'.
Then note that at line 27 make is clearing the 'updating' flag on a different
object '../../x86-linux-fedora-4/include/ual/File.h'. This file was found via
a 'vpath %.h ../../x86-linux-fedora-4/include' statement in the makefile. The
key point here is that the 'updating' flag was set on one object, but cleared
on a different object -- which leaves one object floating around with the
'updating' flag still set.
Then later at lines 41-56, we find the following:
41 ......BEG update: (1) ual.a(FileNotFoundException.o) (0x9059780)
42 .......BEG update: (1) ual.a(FileNotFoundException.o) (0x9059780)
43 ........BEG update: (1) FileNotFoundException.o (0x9056da0)
44 .........BEG update: (1) FileNotFoundException.cpp (0x905ec00)
45 ..........BEG update: (1) FileNotFoundException.cpp (0x905ec00)
46 ..........END update: (0) FileNotFoundException.cpp (0x905ec00)
47 .........END update: (0) ../FileNotFoundException.cpp (0x905ec00)
48 .........BEG update: (1) .dfiles/.mkdir (0x905b040)
49 .........END update: (0) .dfiles/.mkdir (0x905b040)
50 .........BEG update: (1) ../FileNotFoundException.cpp (0x905ec00)
51 .........END update: (0) ../FileNotFoundException.cpp (0x905ec00)
52 make[2]: Circular FileNotFoundException.o <- ual/File.h dependency
dropped.
53 make[2]: Circular FileNotFoundException.o <- ual/FileNotFoundException.h
dependency dropped.
54 ........END update: (0) FileNotFoundException.o (0x9056da0)
55 .......END update: (0) ual.a(FileNotFoundException.o) (0x9059780)
56 ......END update: (0) ual.a(FileNotFoundException.o) (0x9059780)
In this case a different target is being updated. It also depends on
'ual/File.h'. Once the traversal hits u'al/File.h', a false circular
dependency is reported because the 'updating' flag on 'ual/File.h' was never
cleared. Ditto for 'ual/FileNotFoundException.h' (See lines 28-47). Both of
these are false warnings -- there is no circular dependency.
It appears (though it is completely non-obvious) that the 'struct file*'
argument is replaced by a new 'struct file*' argument for the vpath-resolved
object. The 'updating' flag is propagated to the new 'struct file*' object
from the original. Thus at the end of both of the above functions the
'updating' flag needs to be cleared on both the original and the new
'vpath-resolved' object. Failure to do both results in false circular
dependency warnings.
The fix for this bug is to save the original 'struct file* file' argument
into a variable named 'struct file* orig_file' and then invoke the
'finish_updating(file)' macro on both the 'orig_file' and 'file' objects.
I have attached a copy of remake.c that contains the fix for this bug. Just
look for the TEKTRONIX_CIRCULAR_FIX conditionals. This was based on the
V3.81 version of remake.c. Just set the above conditional and compile. This
file also contains a fix for #14927, which is activated by setting the
TEKTRONIX_AR_FIX to 1. These fixes are mutually exclusive.
I'd like to know if this fix resolves the problems others have reported.
Post your results as follow-ups to this bug.
Thanks,
Reid Madsen
Tektronix Inc.
Richardson, Texas
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