[Bug other/91972] New: Bootstrap should use -Wmissing-declarations

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91972

            Bug ID: 91972
           Summary: Bootstrap should use -Wmissing-declarations
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amonakov at gcc dot gnu.org
  Target Milestone: ---

In the good old days when gcc was written in C, bootstrap stage2/3 enabled
-Wmissing-prototypes and so it caught attempted definitions of functions that
should be static, but were not declared so.

Transition to C++ did not change -Wmissing-prototypes to
-Wmissing-declarations, so over time several violations crept in. In particular
this penalizes optimization during non-LTO bootstrap (the compiler has to
assume the function might be used in another TU, even though in reality all
uses are in current file and it simply misses the 'static' keyword).