On 2010-12-06 09:14:15 +0900, Charles Plessy wrote: > - I do not understand what problem the patch solves when reordering ‘-lm -lz > -L.. -lbam’ to ’-L.. -lbam -lm -lz’. It seems that it is related to the use > of --as-needed. Is there a general explanation somewhere, that I can use > when forwarding the patch upstream ?
Here is a part of the build log from Lucas' Ubuntu archive rebuild: ,----[ http://people.ubuntuwire.org/~lucas/ubuntu-nbs/32/samtools_0.1.10-1_lubuntu32.buildlog ]- | gcc -g -Wall -O2 -I.. calDepth.c -o calDepth -lm -lz -L.. -lbam | ../libbam.a(bgzf.o): In function `deflate_block': | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:272: undefined reference to `deflate' | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:274: undefined reference to `deflateEnd' | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:266: undefined reference to `deflateInit2_' | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:290: undefined reference to `deflateEnd' | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:306: undefined reference to `crc32' | /build/user-samtools_0.1.10-1-i386-phvH6d/samtools-0.1.10/bgzf.c:307: undefined reference to `crc32' `---- I'm no expert on this topic but as far as I understand it it's because -lbam (libbam.a) uses symbols from -lz and order matters with --as-needed. ,----[ 3rd paragraph for '-l' in 'man ld' ]- | The linker will search an archive only once, at the location where | it is specified on the command line. If the archive defines a | symbol which was undefined in some object which appeared before the | archive on the command line, the linker will include the | appropriate file(s) from the archive. However, an undefined symbol | in an object appearing later on the command line will not cause the | linker to search the archive again. | [...] | This type of archive searching is standard for Unix linkers. `---- Changing the order makes -lz gets processed after -lbam (which needs symbols from -lz). Michael -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20101206021528.ga26...@vorlon.ping.de
