Bug 1306097 - gcc6 fails to build a correct nunc-stans.so for 389-ds-base
gcc6 fails to build a correct nunc-stans.so for 389-ds-base
Product: Fedora
Classification: Fedora
Component: gcc (Show other bugs)
x86_64 Linux
unspecified Severity medium
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Assigned To: Jakub Jelinek
Fedora Extras Quality Assurance
Depends On:
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Reported: 2016-02-09 20:39 EST by wibrown@redhat.com
Modified: 2016-02-10 03:20 EST (History)
6 users (show)

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Doc Type: Bug Fix
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Last Closed: 2016-02-10 03:20:57 EST
Type: Bug
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Description wibrown@redhat.com 2016-02-09 20:39:30 EST
Description of problem:
Whet you build nunc-stans with gcc5, the output of readelf -Ws shows:

   Num:    Value          Size Type    Bind   Vis      Ndx Name
   107: 0000000000005c50    52 FUNC    GLOBAL DEFAULT   11 abstraction_increment

When you build this with gcc6, you receive:

   Num:    Value          Size Type    Bind   Vis      Ndx Name
    13: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND abstraction_increment

When you then compile another application and attempt to link to nunc-stans, this fails with:

../nunc-stans-0.1.7/lib/libnunc-stans.so: undefined reference to `abstraction_increment'

The definition of abstraction_increment is:

INLINE atom_t abstraction_increment( atom_t *value )

Where INLINE is a macro to:

#define INLINE                extern __forceinline

There are a number of other functions in nunc-stans that use our INLINE macro. For example:

INLINE atom_t abstraction_cas( volatile atom_t *destination, atom_t exchange, atom_t compare )

In both gcc5 and 6 this works correctly:

5   Num:    Value          Size Type    Bind   Vis      Ndx Name
    64: 0000000000005ba0   162 FUNC    GLOBAL DEFAULT   11 abstraction_dcas

6   Num:    Value          Size Type    Bind   Vis      Ndx Name
    65: 0000000000005cc0   162 FUNC    GLOBAL DEFAULT   12 abstraction_dcas

Version-Release number of selected component (if applicable):

How reproducible:
Always. This always and only affects abstraction_increment in this code base.

Steps to Reproduce:
1. Build the 389-ds rpm that includes nunc-stans

Actual results:
Build fails.

Expected results:
Build succeeds.

Additional info:
Happy to help providing any information as required to solve this.
Comment 1 Jakub Jelinek 2016-02-10 03:20:57 EST
This is a flaw in the library.  Please read something about GNU89 inline vs. C99 inline, GCC these days defaults to C11 and therefore the C99 inline semantics is used by default.  INLINE doesn't expand to extern __forceinline as you wrote, but just to inline.  And in C99, that means that the function may be inlined, but an external symbol is not emitted.  You'd need extern inline for that purpose.  Though of course, it is questional why do you use in a translation unit that contains just that function an INLINE at all, there is nothing to inline it into.  If you want to support still older GCC versions and/or building with -std=gnu89, where the GNU89 inline semantics is present, you might want to do something like
#define INLINE extern inline
#define INLINE inline
in the GCC header snippets.  That of course assumes you only use INLINE in the GNU89 inline or C99 extern inline way, not e.g. static INLINE etc.

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