On 04/09/16 08:12, Richard Biener wrote:
On September 3, 2016 5:23:35 PM GMT+02:00, Tom de Vries <tom_devr...@mentor.com> wrote:>Hi, > >this patch fixes a c++ ICE, a p1 6/7 regression. > > >Consider test.C: >... >void bar (__builtin_va_list &); > >struct c >{ > operator const __builtin_va_list &(); > operator __builtin_va_list &(); >}; > >void >foo (void) { > struct c c1; > > bar (c1); >} >... > >The compiler ICEs as follows: >... >test.C: In function ‘void foo()’: >test.C:13:10: internal compiler error: canonical types differ for >identical types __va_list_tag [1] and __va_list_tag [1] > bar (c1); > ^ >comptypes(tree_node*, tree_node*, int) > src/gcc/cp/typeck.c:1430 >reference_related_p(tree_node*, tree_node*) > src/gcc/cp/call.c:1415 >reference_binding > src/gcc/cp/call.c:1559 >implicit_conversion > src/gcc/cp/call.c:1805 >build_user_type_conversion_1 > src/gcc/cp/call.c:3776 >reference_binding > src/gcc/cp/call.c:1664 >implicit_conversion > src/gcc/cp/call.c:1805 >add_function_candidate > src/gcc/cp/call.c:2141 >add_candidates > src/gcc/cp/call.c:5394 >perform_overload_resolution > src/gcc/cp/call.c:4066 >build_new_function_call(tree_node*, vec<tree_node*, va_gc, vl_embed>**, > bool, int) > src/gcc/cp/call.c:4143 >finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool, > bool, int) > src/gcc/cp/semantics.c:2440 >... > >The regression is caused by the commit for PR70955, that adds a >"sysv_abi va_list" attribute to the struct in the va_list type (which >is >an array of one of struct). > >The ICE in comptypes happens as follows: we're comparing two versions >of >va_list type (with identical array element type), each with the >canonical type set to themselves. Since the types are considered >identical, they're supposed to have identical canonical types, which is
Did you figure out why they are not assigned the same canonical type?
When constructing the first type in ix86_build_builtin_va_list_64, it's cached.
When constructing the second type in build_array_type_1 (with call stack: grokdeclarator -> cp_build_qualified_type_real -> build_cplus_array_type -> build_cplus_array_type -> build_array_type -> build_array_type_1), we call type_hash_canon.
But the cached type has name __builtin_sysv_va_list, and the new type has no name, so we hit the clause 'TYPE_NAME (a->type) != TYPE_NAME (b->type)' in type_cache_hasher::equal.
Consequently, TYPE_CANONICAL for the new type remain set to self. Thanks, - Tom
