[postgis-tickets] [PostGIS] #4667: Fails to build with GCC-10

[PostGIS]

#4667: Fails to build with GCC-10
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  Reporter:  Bas Couwenberg         |      Owner:  Raúl Marín
      Type:  defect                 |     Status:  new
  Priority:  medium                 |  Milestone:
 Component:  build/upgrade/install  |    Version:  3.0.x
Resolution:                         |   Keywords:
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Comment (by Bas Couwenberg):

 That also looks like what the [http://gcc.gnu.org/gcc-10/porting_to.html
 porting guide] documents:
 > **Default to -fno-common**
 >
 > A common mistake in C is omitting `extern` when declaring a global
 variable in a header file. If the header is included by several files it
 results in multiple definitions of the same variable. In previous GCC
 versions this error is ignored. GCC 10 defaults to `-fno-common`, which
 means a linker error will now be reported. To fix this, use `extern` in
 header files when declaring global variables, and ensure each global is
 defined in exactly one C file. If tentative definitions of particular
 variables need to be placed in a common block,
 `__attribute__((__common__))` can be used to force that behavior even in
 code compiled without `-fcommon`. As a workaround, legacy C code where all
 tentative definitions should be placed into a common block can be compiled
 with `-fcommon`.
 >
 > {{{
 >       int x;  // tentative definition - avoid in header files
 >
 >       extern int y;  // correct declaration in a header file
 > }}}

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4667#comment:6>
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