Bug 71482 - Add -Wglobal-constructors warning option
Summary: Add -Wglobal-constructors warning option
Status: NEW
Alias: None
Product: gcc
Classification: Unclassified
Component: c++ (show other bugs)
Version: 7.0
: P3 enhancement
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords: diagnostic, patch
Depends on:
Blocks: new-warning, new_warning
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Reported: 2016-06-09 20:14 UTC by Eric Gallager
Modified: 2021-07-25 02:57 UTC (History)
5 users (show)

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Known to work:
Known to fail:
Last reconfirmed: 2016-06-10 00:00:00

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Description Eric Gallager 2016-06-09 20:14:15 UTC 
Apple's gcc 4.2 has a warning flag called -Wglobal-constructors that they describe in their invoke.texi like this:

    @c APPLE LOCAL begin Wglobal-constructors 6324584
    @item -Wglobal-constructors
    @opindex Wglobal-constructors
    Warn about namespace scope data that requires construction or
    destruction, or functions that use the constructor attribute or the
    destructor attribute.  Additionally warn if the Objective-C GNU
    runtime is used to initialize various metadata.
    @c APPLE LOCAL end Wglobal-constructors 6324584

In their c.opt it says:

    ; APPLE LOCAL begin Wglobal-constructors 6324584
    Wglobal-constructors
    C ObjC C++ ObjC++ Var(warn_global_constructors)
    Warn when global (namespace scope) objects require runtime
    construction or destruction or when functions that use attribute
    constructor or destructor are used.  This is useful to help maintain
    fast program startup and end times.
    ; APPLE LOCAL end Wglobal-constructors 6324584

Apparently this option has been carried forward to clang, as pointed out in bug 71456. It would be useful for FSF GCC to have this warning option, too.
Comment 1 Richard Biener 2016-06-10 07:19:52 UTC 
Confirmed.
Comment 2 Marek Polacek 2019-05-30 16:38:39 UTC 
Patch: https://gcc.gnu.org/ml/gcc-patches/2019-05/msg01860.html
Comment 3 Eric Gallager 2019-05-31 13:47:12 UTC 
(In reply to Marek Polacek from comment #2)
> Patch: https://gcc.gnu.org/ml/gcc-patches/2019-05/msg01860.html

Does Sean have a bugzilla account?
Comment 4 Marek Polacek 2019-05-31 13:52:34 UTC 
(In reply to Eric Gallager from comment #3)
> (In reply to Marek Polacek from comment #2)
> > Patch: https://gcc.gnu.org/ml/gcc-patches/2019-05/msg01860.html
> 
> Does Sean have a bugzilla account?

I don't see it.  Probably not yet.
Comment 5 Fangrui Song 2021-07-24 21:54:49 UTC 
Still wanted.

In llvm-project, compiler-rt is using -Wglobal-constructors. llvm/lib/Support will use it as well.