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POUndefined ref to X, despite libraries linked in correct order
 

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  1. POUndefined ref to X, despite libraries linked in correct order
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    <p>I know there are many of these threads already, but none seem to apply to this problem.</p> <p>I have two projects, each using my Dodge library. One is a fairly large project using much of the library's functionality; the other is a small demo. The make files for each project are identical, and yet the small demo fails to link, with the following errors:</p> <pre><code>../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_read_ihdr': (.text+0x3bc): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_read_ihdr': (.text+0x3d9): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_ihdr': (.text+0x5b9): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_ihdr': (.text+0x5d6): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_init_deflate': (.text+0x9b1): undefined reference to `deflateInit_' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_init_inflate': (.text+0xa43): undefined reference to `inflateInit_' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_end_deflate': (.text+0xa9c): undefined reference to `deflateEnd' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_end_inflate': (.text+0xae0): undefined reference to `inflateEnd' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_inflate': (.text+0xb5f): undefined reference to `inflate' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_deflate': (.text+0xbe6): undefined reference to `deflate' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_idats': (.text+0xcb0): undefined reference to `compress' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_idats': (.text+0xccc): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_idats': (.text+0xceb): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_write_idats': (.text+0xd9d): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_read_idat': (.text+0xe86): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o): In function `png_read_idat': (.text+0xea5): undefined reference to `crc32' ../Dodge/Dodge/lib/libpnglite.a(pnglite.o):(.text+0xec1): more undefined references to `crc32' follow </code></pre> <p>The references refer to libz. I used to following command to link the binary:</p> <pre><code>g++ ./main.o -o demo -L../Dodge/Dodge/lib -L/usr/lib -lDodge -lX11 -lGLESv2 -lEGL -lpnglite -lz -lBox2D `sdl-config --libs` -lSDLmain -lSDL -lSDL_mixer </code></pre> <p>As you can see -lz comes after -lpnglite. The static libraries libz.a and libpnglite.a are located in ../Dodge/Dodge/lib. I've tried playing about with the order to no avail.</p> <p>If I remove the following line from the code it links successfully. Strangely, the same line exists in the larger project, which encounters no problems.</p> <pre><code> tex0 = pTexture_t(new Texture(node)); </code></pre> <p>Texture's constructor uses pnglite, and is not declared inline fyi (if that's relevant).</p> <p>Does anyone have any clue as to what might be happening here? I've been using C++ for years, and this is the first time in ages I've been stumped by a linker error.</p> <p>Here are the two make files:</p> <pre><code>DODGE_LOCATION = ../Dodge NAME = platformer CC = g++ CFLAGS = -std=c++0x -O3 -Wall `sdl-config --cflags` -DLINUX -g -DDEBUG INCL = -I$(DODGE_LOCATION)/Dodge/include LIBS = -L$(DODGE_LOCATION)/Dodge/lib -L/usr/lib -lDodge -lX11 -lGLESv2 -lEGL -lpnglite -lz -lBox2D `sdl-config --libs` -lSDLmain -lSDL -lSDL_mixer SRC = src OBJS = $(SRC)/Application.o \ $(SRC)/Item.o \ $(SRC)/GameLogic.o \ $(SRC)/GameSettings.o \ $(SRC)/main.o \ $(SRC)/Menu.o \ $(SRC)/MenuItem.o \ $(SRC)/Player.o \ $(SRC)/SoundFx.o \ $(SRC)/StartMenu.o all: $(OBJS) $(CC) $(OBJS) -o $(NAME) $(LIBS) $(OBJS): %.o: %.cpp $(CC) -c $(CFLAGS) $(INCL) $&lt; -o $@ clean: rm -f $(SRC)/*.o </code></pre> <p>and the one that doesn't link:</p> <pre><code>DODGE_LOCATION = ../Dodge NAME = demo CC = g++ CFLAGS = -std=c++0x -O3 -Wall `sdl-config --cflags` -DLINUX -g -DDEBUG INCL = -I$(DODGE_LOCATION)/Dodge/include LIBS = -L$(DODGE_LOCATION)/Dodge/lib -L/usr/lib -lDodge -lX11 -lGLESv2 -lEGL -lpnglite -lz -lBox2D `sdl-config --libs` -lSDLmain -lSDL -lSDL_mixer SRC = . OBJS = $(SRC)/main.o all: $(OBJS) $(CC) $(OBJS) -o $(NAME) $(LIBS) $(OBJS): %.o: %.cpp $(CC) -c $(CFLAGS) $(INCL) $&lt; -o $@ clean: rm -f $(SRC)/*.o </code></pre> <p>The two projects are located in the same level of the directory tree, and as you can see the make files are the same. I run the make utility from the same terminal (just cd to project's directory), meaning the environment vars are the same too. I can't think of any other factors that might differentiate the two projects. As I said, the offending line in the project that fails is also present in the project that succeeds. Am I missing something obvious here?</p> <p>Thanks in advance</p>
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    1. USWerner Henze
    1. USRJinman
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    1. COAre you absolutely positively sure that /usr/lib/libz.so does not come into play here? Run `ldd` on your executables.
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      1. POUndefined ref to X, despite libraries linked in correct order
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    2. COHmm it seems that libz is being linked dynamically even when I explicitly request that it shouldn't be with -Wl,-Bstatic. I don't see how this explains the problem though.
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      1. POUndefined ref to X, despite libraries linked in correct order
      1. USRJinman
    3. COThere is a lot of reasons actually why dynamic libz can be linked, and a lot of reasons why it can be *not* linked. When it is linked, you don't have undefined references, and when it's not linked, you do have them. Which means your private libz does not resolve them. Perhaps it's of a wrong architecture. So your solution should be two-fold: (1) make sure your libz is correct and resolves the symbols and (2) there is no dynamic libz. (2) could prove problematic as you use a lot of 3rd party libraries that could depend on dynamic libz. Good luck.
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      1. POUndefined ref to X, despite libraries linked in correct order
      1. USn.m.
 

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