Diff for /wikisrc/pkgsrc/gcc.mdwn between versions 1.8 and 1.11

version 1.8, 2017/12/30 02:01:59 version 1.11, 2018/01/01 23:27:13
Line 18  build gcc versions (typically newer vers Line 18  build gcc versions (typically newer vers
 in a compiler within ${PREFIX}, e.g. /usr/pkg/gcc6/bin/gcc.  This  in a compiler within ${PREFIX}, e.g. /usr/pkg/gcc6/bin/gcc.  This
 compiler can then be used to compile other packages.  compiler can then be used to compile other packages.
   
 The Issue with using base system gcc is typically that it is too old,  The issue with using base system gcc is typically that it is too old,
 such as gcc 4.5 with NetBSD 6, which cannot compile c++11.  Another  such as gcc 4.5 with NetBSD 6, which cannot compile c++11.  Another
 example is gcc 4.8 with NetBSD 7.  While this can compile most c++11  example is gcc 4.8 with NetBSD 7.  While this can compile most c++11
 programs, it cannot be used for firefox or glibmm (and therefore any  programs, it cannot be used for firefox or glibmm (and therefore any
Line 26  package that links against glibmm). Line 26  package that links against glibmm).
   
 Issues when using pkgsrc gcc are that  Issues when using pkgsrc gcc are that
   
     - on some platforms, pkgsrc gcc does not build and work
   - it must be bootstrapped, requiring compiling a number of packages    - it must be bootstrapped, requiring compiling a number of packages
     with the system compiler      with the system compiler
   - C++ packages that are linked together should be built with the    - C++ packages that are linked together should be built with the
Line 65  This section attempts to gather all the  Line 66  This section attempts to gather all the 
     clang, when set to use GCC, at least as well as the current      clang, when set to use GCC, at least as well as the current
     scheme.  It is desirable for this logic to work on NetBSD 5.      scheme.  It is desirable for this logic to work on NetBSD 5.
   
     - All systems should work at least as well as they do before
       implementation of new compiler selection logic.
   
   - The compiler selection logic should be understandable and not brittle.    - The compiler selection logic should be understandable and not brittle.
   
 ## Design  ## Design
Line 84  sound while mimimizing complexity. Line 88  sound while mimimizing complexity.
     4.9.      4.9.
   
   - A user-settable variable PKGSRC_GCC_VERSION will declare the    - A user-settable variable PKGSRC_GCC_VERSION will declare the
     version of gcc to be used for C programs, with an OS- and      version of gcc to be used for C programs, with an OS-,
     version--specific default.      version- and architeture- specific default.
   
   - A user-settable variable PKGSRC_GXX_VERSION will declare the    - A user-settable variable PKGSRC_GXX_VERSION will declare the
     version of gcc to be used for all C++ programs, again with an OS-      version of gcc to be used for all C++ programs, again with an OS-,
     and version-specific default.  It must be at least      version- and architeture-specific default.  It must be at least
     PKGSRC_GCC_VERSION.      PKGSRC_GCC_VERSION.
   
     - If PKGSRC_GCC_VERSION and PKGSRC_GXX_VERSION are not set, the
       system will behave much as before.  As a possible exception,
       builds may still fail if the required version is greater than the
       base system version.  So far the only known reason to avoid
       setting these variable is if pkgsrc gcc cannot be built.
   
   - Each of c99, c++, c++11, and c++14 will be associated with a    - Each of c99, c++, c++11, and c++14 will be associated with a
     minimum gcc version, such that almost all programs declaring that      minimum gcc version, such that almost all programs declaring that
     language can be built with that version.  (This avoids issues of      language can be built with that version.  (This avoids issues of
Line 132  sound while mimimizing complexity. Line 142  sound while mimimizing complexity.
     approach is possible inconsistency with gcc's dependencies being      approach is possible inconsistency with gcc's dependencies being
     built with the base compiler and used later.      built with the base compiler and used later.
   
       As an alternative, we store lists of bootstrap packages in a
       variable, because it will vary with OS and version, and with
       PREFER_PKGSRC settings.
   
       As a third alternative, we pass a GCC_BOOTSTRAPPING variable
       recursively.  This is easier but less consistent.
   
   - We hope that the chosen version can be built using the base system    - We hope that the chosen version can be built using the base system
     version, and hope to avoid multi-stage bootstrapping.      version, and hope to avoid multi-stage bootstrapping.
   
Line 149  For now, we defer worrying about these p Line 166  For now, we defer worrying about these p
 will be less serious than the current situation where all c++11  will be less serious than the current situation where all c++11
 programs fail to build on NetBSD 6).  programs fail to build on NetBSD 6).
   
 \todo: Change gcc 4.8 and 4.9 to enable gcc-inplace-math by default.  \todo: Perhaps change gcc 4.8 and 4.9 to enable gcc-inplace-math by
   default.  Perhaps decide that if we want to build gcc, we want to
   build 5 or 6, and 4.9 is no longer of interest as a bootstrap target.
   
 \todo: Analyze what build-time and install-time dependencies actually  \todo: Analyze what build-time and install-time dependencies actually
 exist.  Include old GNU/Linux in this analysis.  exist.  Include old GNU/Linux in this analysis.
Line 212  A gcc version that is too old will not b Line 231  A gcc version that is too old will not b
 Anything older than 4.8 fails for c++11.  4.8 fails on some c++11  Anything older than 4.8 fails for c++11.  4.8 fails on some c++11
 packages, such as firefox and glibmm.  packages, such as firefox and glibmm.
   
 A version that is too new also fails to build packages.  Analyses  A version that is too new also fails to build packages.  Jason Bacon
 posted to tech-pkg indicate that 5 is close to 4.9 in the number of  posted counts to tech-pkg indicate that 5 is close to 4.8 in the
 packages built, and that moving to 6 causes hundreds of additional  number of packages built, and that moving to 6 causes hundreds of
 failures.  additional failures.  (Keep in mind that currently, building with 4.8
   will build 4.9 for firefox, but in the future will not.)
   
       www/pkgsrc/packages/sharedapps/pkg-2017Q3/RHEL6-gcc48/All   16461
       www/pkgsrc/packages/sharedapps/pkg-2017Q3/RHEL6-gcc6/All    15849
   
       www/pkgsrc/packages/sharedapps/pkg-2017Q3/RHEL7-gcc48/All   16414
       www/pkgsrc/packages/sharedapps/pkg-2017Q3/RHEL7-gcc5/All    16338
   
 Therefore, the current answer to "What is the best version to use" is  Therefore, the current answer to "What is the best version to use" is
 5.  5.
   
 \todo Check this with Jason Bacon.  
   
 ### Default versions for various systems  ### Default versions for various systems
   
 Note that if for any particular system's set of installed packages (or  Note that if for any particular system's set of installed packages (or
Line 231  built it earlier. Line 255  built it earlier.
 When the base system is old (e.g., gcc 4.5 in NetBSD 6, or 4.1, in  When the base system is old (e.g., gcc 4.5 in NetBSD 6, or 4.1, in
 NetBSD 5), then it is clear that a newer version must be built.  For  NetBSD 5), then it is clear that a newer version must be built.  For
 these, PKGSRC_GXX_VERSION should default to a newish gcc, avoiding  these, PKGSRC_GXX_VERSION should default to a newish gcc, avoiding
 being so new as to cause building issues.  Currently, gcc5 is probably  being so new as to cause building issues.  PKGSRC_GCC_VERSION should
 a good choice, with gcc6 compiling significantly but not vastly fewer  probably default to the system version if it can build all C99
 packages.  PKGSRC_GCC_VERSION should probably default to the system  programs, or match PKGSRC_GXX_VERSION, if the system version is too
 version if it can build all C99 programs, or match PKGSRC_GXX_VERSION,  old.  Perhaps gcc 4.5 would be used, but 4.1 not used.  \todo Discuss.
 if the system version is too old.  Perhaps gcc 4.5 would be used, but  
 4.1 not used.  \todo Discuss.  
   
 When the base system is almost new enough, the decision about the  When the base system is almost new enough, the decision about the
 default is more complicated.  A key example is gcc 4.8, found in  default is more complicated.  A key example is gcc 4.8, found in
Line 245  need a newer version.  One options is to Line 267  need a newer version.  One options is to
 firefox failing, as well as all c++14 programs.  Another is to choose  firefox failing, as well as all c++14 programs.  Another is to choose
 4.9, but this makes little sense because c++14 programs will still  4.9, but this makes little sense because c++14 programs will still
 fail, and the general rule of moving to the most recent  fail, and the general rule of moving to the most recent
 generally-acceptable version applies, which currently leads to gcc6.  generally-acceptable version applies, which currently leads to gcc5.
 This is in effect a declaration that "almost new enough" does not  This is in effect a declaration that "almost new enough" does not
 count as new enough.  Thus the plan for NetBSD 7 is to set  count as new enough.  Thus the plan for NetBSD 7 is to set
 PKGSRC_GCC_VERSION to 4.8 and PKGSRC_GXX_VERSION to 5.  PKGSRC_GCC_VERSION to 4.8 and PKGSRC_GXX_VERSION to 5.
Line 280  fortran, we should require a single vers Line 302  fortran, we should require a single vers
   
 \todo Discuss.  \todo Discuss.
   
 ### C++ programs used by C programs  ### C++ libraries used by C programs
   
 The choice of one version for C++ and one for C (e.g. 5, 4.8 on  The choice of one version for C++ and one for C (e.g. 5, 4.8 on
 netbsd-7) breaks down if a C program links against a library that is  netbsd-7) breaks down if a C program links against a library that is
Line 294  to really just have one compiler version Line 316  to really just have one compiler version
   
 ## Path forward  ## Path forward
   
   (This assumes per-package marking of bootstrap packages, but is
   reasonably obviously extended to the other schemes.)
   
  - Modify all gcc packages to have minimal dependencies, and to add   - Modify all gcc packages to have minimal dependencies, and to add
    PKGSRC_GCC_BOOTSTRAP.     PKGSRC_GCC_BOOTSTRAP.
   
Line 303  to really just have one compiler version Line 328  to really just have one compiler version
  - Modify the compiler selection logic for LANGUAGES= to fail if   - Modify the compiler selection logic for LANGUAGES= to fail if
    PKGSRC_GCC_VERSION/PKGSRC_GXX_VERSION is not new enough.     PKGSRC_GCC_VERSION/PKGSRC_GXX_VERSION is not new enough.
   
  - Modify the compiler selection logic for GCC_REQD to fail if the   - Modify the compiler selection logic for GCC_REQD to fail if
    version of GCC/GXX is not new enough.     PKGSRC_GCC_VERSION/PKGSRC_GXX_VERSION is not new enough.
   
  - Decide on defaults.  The straw proposal is that PKGSRC_GCC_VERSION   - Decide on defaults.  The straw proposal is that PKGSRC_GCC_VERSION
    is the base system version if >= 4.5 (or 4.4?), and otherwise 5,     is the base system version if >= 4.5 (or 4.4?), and otherwise 5,
    and that PKGSRC_GXX_VERSION is the base system version if >= 5, and     and that PKGSRC_GXX_VERSION is the base system version if >= 5, and
    otherwise 5.     otherwise 5.  Implement these in platform.mk as they are tested.
   
 ### Later steps  ### Later steps
   
  - Address fortran.   - Address fortran.  Probably add PKGSRC_GFORTRAN_VERSION, after
      determining how Fortran, C and C++ interact with library ABI
      compatibility.

Removed from v.1.8  
changed lines
  Added in v.1.11


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