[Bug c++/71835] New: ICE on invalid C++ code with ambiguous overloaded operators: tree check: expected tree that contains ‘decl minimal’ structure, have ‘pointer_type’ in convert_like_real, at cp/call.c:6549

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71835

            Bug ID: 71835
           Summary: ICE on invalid C++ code with ambiguous overloaded
                    operators: tree check: expected tree that contains
                    ‘decl minimal’ structure, have ‘pointer_type’ in
                    convert_like_real, at cp/call.c:6549
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following C++ code causes an ICE when compiled with the current GCC trunk
on x86_64-linux-gnu in both 32-bit and 64-bit modes.  

It also affects 6.1.x and is a regression from 5.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160710 (experimental) [trunk revision 238196] (GCC)
$
$ g++-5.4 -c small.cpp
small.cpp: In function ‘void f()’:
small.cpp:7:18: error: conversion from ‘C’ to ‘void (*)(int)’ is ambiguous
 void f () {  c (0);  }
                  ^
small.cpp:4:13: note: candidate: B::operator void (*)(int)()
 struct B {  operator T * ();  };
             ^
small.cpp:3:13: note: candidate: A::operator void (*)(int)()
 struct A {  operator T * ();  };
             ^
small.cpp:7:18: note:   initializing argument 'this' of ‘#‘pointer_type’ not
supported by dump_decl#<declaration error>’
 void f () {  c (0);  }
                  ^
$
$ g++-trunk -c small.cpp
small.cpp: In function ‘void f()’:
small.cpp:7:18: error: conversion from ‘C’ to ‘void (*)(int)’ is ambiguous
 void f () {  c (0);  }
                  ^
small.cpp:4:13: note: candidate: B::operator void (*)(int)()
 struct B {  operator T * ();  };
             ^~~~~~~~
small.cpp:3:13: note: candidate: A::operator void (*)(int)()
 struct A {  operator T * ();  };
             ^~~~~~~~
small.cpp:7:18: internal compiler error: tree check: expected tree that
contains ‘decl minimal’ structure, have ‘pointer_type’ in convert_like_real, at
cp/call.c:6549
 void f () {  c (0);  }
                  ^
0x1060764 tree_contains_struct_check_failed(tree_node const*,
tree_node_structure_enum, char const*, int, char const*)
        ../../gcc-source-trunk/gcc/tree.c:9923
0x66de61 contains_struct_check
        ../../gcc-source-trunk/gcc/tree.h:3144
0x66de61 convert_like_real
        ../../gcc-source-trunk/gcc/cp/call.c:6549
0x67ab14 build_op_call_1
        ../../gcc-source-trunk/gcc/cp/call.c:4410
0x67ab14 build_op_call(tree_node*, vec<tree_node*, va_gc, vl_embed>**, int)
        ../../gcc-source-trunk/gcc/cp/call.c:4429
0x8185c7 finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc-source-trunk/gcc/cp/semantics.c:2450
0x791430 cp_parser_postfix_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:6909
0x79a68c cp_parser_unary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:7991
0x79aee7 cp_parser_cast_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:8668
0x79b4e5 cp_parser_binary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:8770
0x79bdd0 cp_parser_assignment_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9058
0x79e6c9 cp_parser_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9225
0x79ee3f cp_parser_expression_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10686
0x78cc7b cp_parser_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10537
0x78d93c cp_parser_statement_seq_opt
        ../../gcc-source-trunk/gcc/cp/parser.c:10809
0x78da2f cp_parser_compound_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10763
0x7ac2cf cp_parser_function_body
        ../../gcc-source-trunk/gcc/cp/parser.c:20701
0x7ac2cf cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc-source-trunk/gcc/cp/parser.c:20737
0x7acd71 cp_parser_function_definition_after_declarator
        ../../gcc-source-trunk/gcc/cp/parser.c:25433
0x7ada85 cp_parser_function_definition_from_specifiers_and_declarator
        ../../gcc-source-trunk/gcc/cp/parser.c:25345
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$


----------------------------------------


typedef void T (int);

struct A {  operator T * ();  };
struct B {  operator T * ();  };
struct C : A, B {} c;

void f () {  c (0);  }