Fix GCC 15.2.1 compilation error: reposition function attributes

[Copilot]

GCC 15.2.1 rejects attributes placed between function signature elements when defining (not declaring) a function. The code had:

void * __attribute__((flatten)) xxmalloc (size_t sz) __attribute__((alloc_size(1))) __attribute__((malloc))

This triggers:

error: attributes are not allowed on a function-definition

Changes

• src/source/libhoard.cpp: Moved all attributes before return type

  __attribute__((flatten)) __attribute__((alloc_size(1))) __attribute__((malloc))
  void * xxmalloc (size_t sz)

• .gitignore: Added build/ and CodeQL artifacts to prevent committing build output

The new syntax is compatible with GCC 15.2.1 while maintaining compatibility with older GCC versions and Clang.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Compile failure in libhoard.cpp with gcc 15.2.1</issue_title>
<issue_description>

/usr/src/Hoard/src/source/libhoard.cpp:100:56: error: attributes are not allowed on a function-definition
  100 |   void * __attribute__((flatten)) xxmalloc (size_t sz) __attribute__((alloc_size(1))) __attribute__((malloc))
      |                                                        ^~~~~~~~~~~~~
make[2]: *** [CMakeFiles/hoard.dir/build.make:93: CMakeFiles/hoard.dir/src/source/libhoard.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:87: CMakeFiles/hoard.dir/all] Error 2
make: *** [Makefile:136: all] Error 2

Also a few redefinition warnings but they're not fatal...

In file included from /usr/src/Hoard/build/_deps/heap-layers-src/locks/all.h:4,
                 from /usr/src/Hoard/build/_deps/heap-layers-src/heaplayers.h:112,
                 from /usr/src/Hoard/src/include/hoard/hoardheap.h:21,
                 from /usr/src/Hoard/src/include/hoard/hoardtlab.h:27,
                 from /usr/src/Hoard/src/source/unixtls.cpp:60:
/usr/src/Hoard/build/_deps/heap-layers-src/locks/spinlock.h:49:9: warning: ‘NO_INLINE’ redefined
   49 | #define NO_INLINE
      |         ^~~~~~~~~
/usr/src/Hoard/build/_deps/heap-layers-src/heaplayers.h:66:9: note: this is the location of the previous definition
   66 | #define NO_INLINE       __attribute__ ((noinline))
      |         ^~~~~~~~~
[ 66%] Building CXX object CMakeFiles/hoard.dir/src/source/libhoard.cpp.o
In file included from /usr/src/Hoard/build/_deps/heap-layers-src/locks/all.h:4,
                 from /usr/src/Hoard/build/_deps/heap-layers-src/heaplayers.h:112,
                 from /usr/src/Hoard/src/source/libhoard.cpp:32:
/usr/src/Hoard/build/_deps/heap-layers-src/locks/spinlock.h:49:9: warning: ‘NO_INLINE’ redefined
   49 | #define NO_INLINE
      |         ^~~~~~~~~
/usr/src/Hoard/build/_deps/heap-layers-src/heaplayers.h:66:9: note: this is the location of the previous definition
   66 | #define NO_INLINE       __attribute__ ((noinline))

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Compile failure in libhoard.cpp with gcc 15.2.1 #80

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[emeryberger]

@copilot I want you to verify this builds under GCC 15.2.1.

[Copilot]

@copilot I want you to verify this builds under GCC 15.2.1.

Verified successful build with GCC 15.2.0 using the official GCC Docker container.

Test Results:

• ✅ Old syntax: Produces error "attributes are not allowed on a function-definition"
• ✅ New syntax: Compiles successfully with no errors
• ✅ Full Hoard library: Builds successfully (libhoard.so created)

The only warnings are the non-fatal NO_INLINE redefinition warnings from the Heap-Layers dependency mentioned in the original issue.

Build completed with commit e469973.