Xcode warnings: could not open OSO file

Question

I upgraded the ffmpeg dylibs in my Xcode project to a new version and now I get all these warnings in the Xcode console window when I run my app. Any ideas why I'm getting these?

Thanks in advance!

Here's an abbreviated version, but you'll get the idea.

warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/4xm.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/4xm.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/8bps.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/8bps.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/8svx.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/8svx.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/a64multienc.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/a64multienc.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_ac3_parser.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_ac3_parser.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_adtstoasc_bsf.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_adtstoasc_bsf.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_parser.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aac_parser.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacadtsdec.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacadtsdec.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aaccoder.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aaccoder.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacdec.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacdec.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacenc.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacenc.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacps.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacps.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacpsy.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacpsy.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacsbr.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aacsbr.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aactab.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aactab.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aandcttab.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aandcttab.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aasc.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/aasc.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3_parser.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3_parser.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dec.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dec.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dec_data.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dec_data.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dsp.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3dsp.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_combined.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_combined.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_fixed.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_fixed.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_float.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3enc_float.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3tab.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/ac3tab.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/acelp_filters.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/acelp_filters.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib
warning: .o file "/Users/username/Downloads/ffmpeg-0.8.5/libavcodec/acelp_pitch_delay.o" more recent than executable timestamp in "/Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib"
warning: Could not open OSO file /Users/username/Downloads/ffmpeg-0.8.5/libavcodec/acelp_pitch_delay.o to scan for pubtypes for objfile /Users/username/Library/Developer/Xcode/DerivedData/MyApp-cjpuovfvlxckuddiuysbbosqgbsj/Build/Products/Debug/MyProject.framework/Versions/A/Libraries/libavcodec.dylib

Answer 1

How to neutralize "Could not open OSO" and force the "o"s to load:

---

Disclaimer: you should not do this :)

---

As explained previously, the error messages tell you that your debug info is the incorrect info for your dylib.

However, if for some exotic reason you believe that your "o" files—stained though they may be with bad timestamps—really do contain proper info and you need them loaded in gdb, then proceed...

For the sample code below, I assume an o file named abcdefg.o and a dylib named lib_jklmnop.dylib

---

Step One. Run this command:

nm -ap lib_jklmnop.dylib  | grep OSO | awk '{printf("%s %s\n", toupper($1), $0 )}'

The output should contain:

00000000560D902C 00000000560d902c - 03 0001   OSO /some/file/path/abcdefg.o

Note: you must find an output line with "abcdefg.o" in it. We are fixing the OSO warning for only one file: abcdefg.o, so if you do not use the timestamp corresponding to that file then the following steps are pointless.

Step Two. Take the hexadecimal number in the first column (560D902C in this example), and run it through python like so:

echo import datetime\; t=datetime.datetime.fromtimestamp\( 0x560D902C \) \; print \( t.strftime\(\'%Y%m%d%H%M.%S\'\) \) | python3

(You could use perl or something else for this step. Python seemed accessible and portable for demonstration purposes.) The above will take the "0x560D902C" and produce a formatted timestamp: 201510011257.32

Step Three. Using the formatted timestamp obtained from step 2, run the touch command to alter the timestamp on abcdefg.o:

touch -t 201510011257.32  abcdefg.o

Now the timestamp on the "o" matches the OSO entry in the dylib. GDB will load this "o" file.

(For posterity: tested on Mac OS X 10.8.5 with GNU gdb 6.3.50-20050815 Apple version gdb-1824)

Recommended reading:

Apple DWARF debug scheme

Bugzilla@Mozilla - GDB complains of .o files having newer timestamp than executable

Answer 2

When I see this, I often found that clean and rebuild will fix the warnings.

Answer 3

I had been tolerating this "Could not open OSO file" output in gdb for several weeks. Casual googling always brought me back here.

@kakyo's answer (try a rebuild) works, but I wanted to know more.

Essential (well-known?) background information: both the "o" files and the "dylib" files are produced during a build. The "o" files contain debug info. However, when the linker links the "o" files to create a "dylib", that debug info is not placed into the resulting dylib.

The warnings announce that the timestamp on the "o" file is more recent than the timestamp on the "dylib". Actually—and this distinction is crucial—the warnings compare the time of the "o" file to a timestamp in the dylib. You can view the OSO-related timestamps in a dylib using this command:

bash_prompt$ nm -ap libavcodec.dylib  | grep OSO

00000000560d913f - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/4xm.o
00000000560d913f - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/8bps.o
00000000560d913e - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/8svx.o
00000000560d913e - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/a64multienc.o
00000000560d9140 - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/aac_parser.o
00000000560d9141 - 03 0001   OSO /Downloads/ffmpeg-0.8.5/libavcodec/aaccoder.o

Please note: The hexadecimal values in the first column are timestamps.

GDB (the debugger) finds the o files at the paths recorded in the dylib, and then GDB checks the timestamps.

It seems the most obvious use case for this timestamp-checking feature is as follows:

1. Your product (your company's "flagship application", let's say) ships with some third-party dylib (like the ffmpeg dylibs) inside your app bundle.
2. You launch your application under GDB, and your application loads the third-party dylib.
3. Oops! Your app bundle contains an outdated copy of third_party.dylib. You actually built a fresh third_party.dylib yesterday (which produced a fresh dylib and fresh "o" files). Those fresh third-party items are all in "~/third_party/other_folder", and you forgot to copy the latest third_party.dylib into your app bundle.

Assuming third_party.dylib is always built in the same (project-external) directory, then these timestamp-checks are one way to alert you to exactly the "Oops!" described above. Your out-dated copy of third_party.dylib (the copy in your app bundle) has "OSO" entries pointing to "~/third_party/other_folder/someclass.o", but the debugger is alerting you to the fact that "~/third_party/other_folder/someclass.o" has been recently re-compiled, and you appear to not be using the dylib corresponding to the latest compilation.

Interesting Trivia: The error says "more recent than executable timestamp" [emphasis is mine]—but that isn't always true! The error will appear if the timestamp is either newer or older than what the dylib OSO entry expects. The error appears when a test of strict timestamp equality fails. View the relevant gdb source code here:

https://github.com/unofficial-opensource-apple/gdb/blob/ae8094e0d84d94fc0ad9b5ecdcd79acd722879f8/src/gdb/dbxread.c http://www.opensource.apple.com/source/gdb/gdb-952/src/gdb/dbxread.c

Final note: to actually resolve the "Could not open OSO" error, please return to @kakyo's original correct advice