CODEWITHSUNDEEP
c++macosqtlibpng
strnmn
strnmn

Reputation: 565

libpng | duplicate symbol for architecture

I'm trying to compile a project using libpng on Mac OS X Yosemite.

I got the error:

Undefined symbols for architecture x86_64:
  "_png_create_info_struct", referenced from:
      _writePNG in qrenc.o
  "_png_create_write_struct", referenced from:
      _writePNG in qrenc.o
  "_png_destroy_write_struct", referenced from:
      _writePNG in qrenc.o
  "_png_init_io", referenced from:
      _writePNG in qrenc.o
  "_png_set_IHDR", referenced from:
      _writePNG in qrenc.o
  "_png_set_PLTE", referenced from:
      _writePNG in qrenc.o
  "_png_set_longjmp_fn", referenced from:
      _writePNG in qrenc.o
  "_png_set_pHYs", referenced from:
      _writePNG in qrenc.o
  "_png_set_tRNS", referenced from:
      _writePNG in qrenc.o
  "_png_write_end", referenced from:
      _writePNG in qrenc.o
  "_png_write_info", referenced from:
      _writePNG in qrenc.o
  "_png_write_row", referenced from:
      _writePNG in qrenc.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

so I added -lpng to my ld call. Now it throws

duplicate symbol _main in:
    .obj/main.o
    .obj/qrenc.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Same error when linking against libpng installed by homebrew.

What am I doing wrong?

Upvotes: 1

Views: 542

Answers (1)

Anton Malyshev
Anton Malyshev

Reputation: 8861

You have two files (probably main.c and qrenc.c) with main function. Remove the function from any of these files and use -lpng.

Upvotes: 3

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