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= RPM Macros for Build Flags <!-- The name of your change proposal --> =
= RPM Macros for Build Flags <!-- The name of your change proposal --> =
{{Change_Proposal_Banner}}


== Summary ==
== Summary ==
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Create a corresponding macro for each compiler flag in the redhat-rpm-config macro file and create "extra flag" macros to make it easier for packages to control the set of default flags.
Create "extra flag" macros to make it easier for packages to add to the default list of compiler flags.


== Owner ==
== Owner ==
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== Current status ==
== Current status ==
[[Category:ChangePageIncomplete]]
[[Category:ChangeAcceptedF38]]
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[[Category:SystemWideChange]]
[[Category:SystemWideChange]]


* Targeted release: [[Releases/37 | Fedora Linux 37 ]]  
* Targeted release: [[Releases/38 | Fedora Linux 38 ]]  
* Last updated: <!-- this is an automatic macro — you don't need to change this line -->  {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}  
* Last updated: <!-- this is an automatic macro — you don't need to change this line -->  {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}  
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ON_QA -> change is fully code complete
ON_QA -> change is fully code complete
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* FESCo issue: <will be assigned by the Wrangler>
* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/SNV72TC5SDPUSQEVULKRKPIJE2ZMQUIP/ devel thread]
* Tracker bug: <will be assigned by the Wrangler>
* FESCo issue: [https://pagure.io/fesco/issue/2805 #2805]
* Release notes tracker: <will be assigned by the Wrangler>
* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2100610 #2100610]
* Release notes tracker: <will not assigned by the Wrangler -- not user-facing>


== Detailed Description ==
== Detailed Description ==
<!-- Expand on the summary, if appropriate.  A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
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The macros file in the redhat-rpm-config package contains a list of default compiler flags for packages to use when compiling C,C++, and Fortran packages.  There is currently no standard way to remove or add to the set of default flags.  Most packages use a combination of echo and sed to remove unwanted flags or add new ones.  Some examples:
The macros file in the redhat-rpm-config package contains a list of default compiler flags for packages to use when compiling C, C++, and Fortran packages.  This change will add new macros to redhat-rpm-config which will make it easier for packages to add their own compiler flags.
    compiler-rt: [https://src.fedoraproject.org/rpms/compiler-rt/blob/rawhide/f/compiler-rt.spec#_6 global optflags %(echo %{optflags} -D_DEFAULT_SOURCE)]
    julia:      [https://src.fedoraproject.org/rpms/julia/blob/rawhide/f/julia.spec#_267 %global optflags %(echo %{optflags} | sed 's/-Wp,-D_GLIBCXX_ASSERTIONS //')]


This change will add new macros which will make it easier for packages to add and remove their own compiler flags.  This strategy is already used to some extent with feature macros like %{_lto_cflags}, %{_hardening_cflags}, etc, but these new flags will give packagers more fine-grained control over the options.
The proposed macros for adding new flags are:
 
The proposed new macros macros for adding new flags are:


     %_pkg_extra_cflags
     %_pkg_extra_cflags
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     %_pkg_extra_ldflags
     %_pkg_extra_ldflags


These will be added to %{build_cflags}, %{build_cxxflags}, %{build_fflags}, and %{build_ldflags} respectively to allow packges to add their own flags to the default list: e.g.
These will be added to %{build_cflags}, %{build_cxxflags}, %{build_fflags}, and %{build_ldflags} respectively to allow packages to add their own flags to the default list: e.g.


     %build_cflags %{optflags} %{_pkg_extra_cflags}
     %build_cflags %{optflags} %{_pkg_extra_cflags}
The proposed new macros to represent existing flags are:
    %_flag_fstack_protector_strong    -fstack-protector-strong
    %_flag_z_now                      -Wl,-z,now
    %_flag_z_defs                      -Wl,-z,defs
    %_flag_flto_auto                  -flto=auto
    %_flag_ffat_lto_objects            -ffat-lto-objects
    %_flag_o                          -O2
    %_flag_f_exceptions                -fexceptions
    %_flag_g                          -g
    %_flag_grecord_gcc_switches        -grecord-gcc-switches
    %_flag_pipe                        -pipe
    %_flag_wall                        -Wall
    %_flag_werror_format_security      -Werror=format-security
    %_flag_fortify_source              -Wp,-D_FORTIFY_SOURCE=2
    %_flag_glibcxx_assertions          -Wp,-D_GLIBCXX_ASSERTIONS
    %_flag_asynchronous_unwind_tables  -fasynchronous-unwind-tables
    %_flag_fstack_clash_protection    -fstack-clash-protection
    %_flag_fcf_protection              -fcf-protection
    %_flag_mbranch_protection_standard -mbranch-protection=standard
With these new macros, the examples from above could be re-written as:
    compiler-rt: %global _pkg_extra_cflags -D_DEFAULT_SOURCE
    julia:      %global _flag_glibcxx_assertions %{nil}
For more details see the [https://src.fedoraproject.org/fork/tstellar/rpms/redhat-rpm-config/c/0ee9a8c989b55c631f870ad311cdca87329034be?branch=macro-flags Prototype Implementation]
In addition to adding these new macros, the packaging guidelines will be updated to require that all new flags added to redhat-rpm-config have their own RPM macro.


== Feedback ==
== Feedback ==
<!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->
<!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->
The original proposal would have replaced every existing compiler flag in redhat-rpm-config with it's own macro.  However, it was determined that this may be a little bit too confusing since there would be ambiguity about whether, for example, %global _flag_f_exceptions %{nil} would actually disable exceptions by adding -fno-exceptions to the flags or if it would just remove the -fexceptions flag.  Rather than hold up other useful and fairly straight-forward changes in this proposal, the proposal owners decided to drop the flag macros from this proposal.  It could be revisited in a later release.


== Benefit to Fedora ==
== Benefit to Fedora ==
* It will provide a standard way to disable existing compiler flags or enable new ones that is more simple than the existing echo + grep solution.
* It will provide a standard way to add to the list of default compiler flags.
* It will make it easier to determine which packages disable or modify which flags by doing a simple grep of the spec files.
* It will make it easier to determine which packages add compiler flags by doing a simple grep of the spec files.
* It will make it easier for toolchain developers to experiment with adding new flags to the distribution as this can be done with a simple macro definition instead of patching redhat-rpm-config.
* It will make it easier for toolchain developers to experiment with adding new flags to the distribution as this can be done with a simple macro definition instead of patching redhat-rpm-config.
<!-- What is the benefit to the distribution?  Will the software we generate be improved? How will the process of creating Fedora releases be improved?
<!-- What is the benefit to the distribution?  Will the software we generate be improved? How will the process of creating Fedora releases be improved?
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<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
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* Release engineering: [https://pagure.io/releng/issues #Releng issue number] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Release engineering: [https://pagure.io/releng/issues/10819 #10819] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
<!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.  
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The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->
The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->


* Policies and guidelines: N/A (not needed for this Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Policies and guidelines: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. Please submit a pull request with the proposed changes before submitting your Change proposal. -->
<!-- Do the packaging guidelines or other documents need to be updated for this feature?  If so, does it need to happen before or after the implementation is done?  If a FPC ticket exists, add a link here. Please submit a pull request with the proposed changes before submitting your Change proposal. -->
** The Fedora packaging policy will be updated to require that new flags added to redhat-rpm-config come with their own RPM macro.
** The Fedora packaging policy will be updated to require that packages that want to use additional flag use the new macros.


* Trademark approval: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
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* Contingency mechanism: (What to do?  Who will do it?) Change owner will revert the update to redhat-rpm-config.  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Contingency mechanism: (What to do?  Who will do it?) Change owner will revert the update to redhat-rpm-config.  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
* Contingency deadline: Mass Rebuild <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Contingency deadline: Beta freeze <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
* Blocks release? N/A (not a System Wide Change), No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Blocks release? N/A (not a System Wide Change), No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->

Latest revision as of 14:29, 10 February 2023

RPM Macros for Build Flags

Summary

Create "extra flag" macros to make it easier for packages to add to the default list of compiler flags.

Owner

Current status

Detailed Description

The macros file in the redhat-rpm-config package contains a list of default compiler flags for packages to use when compiling C, C++, and Fortran packages. This change will add new macros to redhat-rpm-config which will make it easier for packages to add their own compiler flags.

The proposed macros for adding new flags are: 

   %_pkg_extra_cflags
   %_pkg_extra_cxxflags
   %_pkg_extra_fflags
   %_pkg_extra_ldflags

These will be added to %{build_cflags}, %{build_cxxflags}, %{build_fflags}, and %{build_ldflags} respectively to allow packages to add their own flags to the default list: e.g. 

   %build_cflags %{optflags} %{_pkg_extra_cflags}

Feedback

The original proposal would have replaced every existing compiler flag in redhat-rpm-config with it's own macro. However, it was determined that this may be a little bit too confusing since there would be ambiguity about whether, for example, %global _flag_f_exceptions %{nil} would actually disable exceptions by adding -fno-exceptions to the flags or if it would just remove the -fexceptions flag. Rather than hold up other useful and fairly straight-forward changes in this proposal, the proposal owners decided to drop the flag macros from this proposal. It could be revisited in a later release.

Benefit to Fedora

  • It will provide a standard way to add to the list of default compiler flags.
  • It will make it easier to determine which packages add compiler flags by doing a simple grep of the spec files.
  • It will make it easier for toolchain developers to experiment with adding new flags to the distribution as this can be done with a simple macro definition instead of patching redhat-rpm-config.

Scope

  • Proposal owners:
    • Proposal owners will update the redhat-rpm-config package and add the new macros.
    • Proposal owners will test the changes to ensure that the correct flags are still being used.
  • Other developers:
    • Other developers may, but are not required to, update their packages to use the new macros.
  • Policies and guidelines:
    • The Fedora packaging policy will be updated to require that packages that want to use additional flag use the new macros.
  • Trademark approval: N/A (not needed for this Change)
  • Alignment with Objectives:

Upgrade/compatibility impact

None.

How To Test

  • This can be tested by inspecting the value of the %{build_cflags}, %{build_cxxflags}, %{build_fflags}, and %{build_ldflags} and ensuring they are the same before and after the change.
  • This can be tested by modifying some of the new macros in a spec file and ensuring that the changes appear in the appropriate macro mentioned above.

User Experience

This is a change for developers and will have no impact to the user experience.

Dependencies

None.

Contingency Plan

  • Contingency mechanism: (What to do? Who will do it?) Change owner will revert the update to redhat-rpm-config.
  • Contingency deadline: Beta freeze
  • Blocks release? N/A (not a System Wide Change), No

Documentation

None.

Release Notes

None.

Retrieved from "https://fedoraproject.org/w/index.php?title=Changes/RPMMacrosForBuildFlags&oldid=668032"