https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86491
--- Comment #1 from Jason Vas Dias <jason.vas.dias at gmail dot com> ---
In investigating this problem, I actually modified 6.4.1's gcc/cp/decl2.c
with the following patch to print out which component of the
base struct it thinks uses the anonymous namespace:
BEGIN PATCH:
--- decl2.c,r260630 2018-05-18 14:47:27.000000000 +0100
+++ decl2.c 2018-07-11 16:16:13.816541340 +0100
@@ -2154,0 +2155,5 @@
+struct tree_vis
+{ tree *tp;
+ int vis;
+};
+
@@ -2158 +2163 @@
- int *vis_p = (int *)data;
+ struct tree_vis *tree_vis_p = (struct tree_vis *)data;
@@ -2166 +2171,2 @@
- *vis_p = VISIBILITY_ANON;
+ tree_vis_p->tp = tp;
+ tree_vis_p->vis = VISIBILITY_ANON;
@@ -2170,2 +2176,4 @@
- && CLASSTYPE_VISIBILITY (*tp) > *vis_p)
- *vis_p = CLASSTYPE_VISIBILITY (*tp);
+ && CLASSTYPE_VISIBILITY (*tp) > tree_vis_p->vis)
+ { tree_vis_p->vis = CLASSTYPE_VISIBILITY (*tp);
+ tree_vis_p->tp = tp;
+ }
@@ -2181,3 +2189,8 @@
- int vis = VISIBILITY_DEFAULT;
- cp_walk_tree_without_duplicates (&type, min_vis_r, &vis);
- return vis;
+ struct tree_vis tv = { NULL, VISIBILITY_DEFAULT };
+ cp_walk_tree_without_duplicates (&type, min_vis_r, &tv);
+ return tv.vis;
+}
+
+static void
+tree_type_visibility (tree_vis *tvis)
+{ cp_walk_tree_without_duplicates (tvis->tp, min_vis_r, tvis);
@@ -2607 +2620,4 @@
- int subvis = type_visibility (TREE_TYPE (t));
+ tree_vis tvis = { &(TREE_TYPE (t)), VISIBILITY_DEFAULT };
+ tree_type_visibility (&tvis);
+
+ int subvis = tvis.vis;
@@ -2627,2 +2643,2 @@
-%qT has a base %qT whose type uses the anonymous namespace",
- type, TREE_TYPE (t));
+%qT has a base %qT whose type uses the anonymous namespace because of its
component %qT",
+ type, TREE_TYPE (t), *tvis.tp);
:END PATCH
But the offending component is actually the whole base class:
N::NT<_C_, _C_OBJ_, _M_>::NT() void N::NA::C::m()
In file included from /tmp/tM.C:1:0:
/tmp/t2.H: At global scope:
/tmp/t2.H:14:9: warning: ‘N::D’ has a base ‘N::NT<N::NA::C, (& N::NA::c_),
&N::NA::C::m>’ whose type uses the anonymous namespace because of its component
‘N::NT<N::NA::C, (& N::NA::c_), &N::NA::C::m>’ [-Wsubobject-linkage]
class D : public NT<NA::C,&NA::c_,&NA::C::m>
^
N::D::D() N::D::D() N::D::D() int main() N::NT<_C_, _C_OBJ_, _M_>::NT() [with
_C_ = N::NA::C; _C_* _C_OBJ_ = (& N::NA::c_); void (_C_::* _M_)() =
&N::NA::C::m] N::NT<_C_, _C_OBJ_, _M_>::NT() [with _C_ = N::NA::C; _C_* _C_OBJ_
= (& N::NA::c_); void (_C_::* _M_)() = &N::NA::C::m] N::NT<_C_, _C_OBJ_,
_M_>::NT() [with _C_ = N::NA::C; _C_* _C_OBJ_ = (& N::NA::c_); void (_C_::*
_M_)() = &N::NA::C::m]
Analyzing compilation unit
Performing interprocedural optimizations
<*free_lang_data> <visibility> <build_ssa_passes> <opt_local_passes>
<targetclone> <free-inline-summary> <whole-program> <inline>Assembling
functions:
<simdclone> void N::NA::C::m() N::D::D() int main() N::NT<_C_, _C_OBJ_,
_M_>::NT() [with _C_ = N::NA::C; _C_* _C_OBJ_ = (& N::NA::c_); void (_C_::*
_M_)() = &N::NA::C::m]
Execution times (seconds)
phase setup : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall
1386 kB (62%) ggc
phase opt and generate : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 (100%) wall
169 kB ( 8%) ggc
integrated RA : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 (100%) wall
96 kB ( 4%) ggc
TOTAL : 0.00 0.00 0.01
2223 kB
It would be nice if the fix for this could also print out more information
about precisely which component of the structure the compiler thinks uses
the anonymous namespace - it has taken me 2 days of analysis to get this
far, which could have been avoided if GCC printed out information like
the above in the first place.
