Support reading void* type from DWARF

* include/abg-ir.h (type_decl::get_void_type_decl): Declare new
	static method.
	* src/abg-ir.cc (type_decl::get_void_type_decl): Define it.
	* src/abg-dwarf-reader.cc (build_ir_node_for_void_type): Define
	new static function.
	(build_pointer_type_def): Support void* type nodes here.
	* tests/data/test-read-dwarf/test5.cc: Source code for new test
	input.
	* tests/data/test-read-dwarf/test5.o: New test input.
	* tests/data/test-read-dwarf/test5.o.abi: Likewise.
	* tests/Makefile.am: Add the above to the source distribution.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

include/abg-ir.h

@@ -886,6 +886,9 @@ public:
 	    location locus, const std::string&	mangled_name = "",
 	    visibility vis = VISIBILITY_DEFAULT);
 
+  static type_decl_sptr
+  get_void_type_decl();
+
   virtual bool
   operator==(const type_base&) const;
 

src/abg-dwarf-reader.cc

@@ -1970,6 +1970,9 @@ build_ir_node_from_die(read_context&	ctxt,
 		       bool		called_from_public_decl,
 		       size_t		where_offset);
 
+static decl_base_sptr
+build_ir_node_for_void_type(read_context& ctxt);
+
 static function_decl_sptr
 build_function_decl(read_context&	ctxt,
 		    Dwarf_Die*		die,
@@ -4554,14 +4557,17 @@ build_pointer_type_def(read_context&	ctxt,
   if (tag != DW_TAG_pointer_type)
     return result;
 
+  decl_base_sptr utype_decl;
   Dwarf_Die underlying_type_die;
   if (!die_die_attribute(die, DW_AT_type, underlying_type_die))
-    return result;
+    // If the DW_AT_type attribute is missing, that means we are
+    // looking at a pointer to "void".
+    utype_decl = build_ir_node_for_void_type(ctxt);
 
-  decl_base_sptr utype_decl =
-    build_ir_node_from_die(ctxt, &underlying_type_die,
-			   called_from_public_decl,
-			   where_offset);
+  if (!utype_decl)
+    utype_decl = build_ir_node_from_die(ctxt, &underlying_type_die,
+					called_from_public_decl,
+					where_offset);
   if (!utype_decl)
     return result;
 
@@ -5321,6 +5327,20 @@ build_ir_node_from_die(read_context&	ctxt,
   return result;
 }
 
+///  Build the IR node for a void type.
+///
+///  @param ctxt the read context to use.
+///
+///  @return the void type node.
+static decl_base_sptr
+build_ir_node_for_void_type(read_context& ctxt)
+{
+  decl_base_sptr t = type_decl::get_void_type_decl();
+  if (!has_scope(t))
+    add_decl_to_scope(t, ctxt.cur_tu()->get_global_scope());
+  return t;
+}
+
 /// Build an IR node from a given DIE and add the node to the current
 /// IR being build and held in the read_context.  Doing that is called
 /// "emitting an IR node for the DIE".

src/abg-ir.cc

@@ -3066,6 +3066,18 @@ type_decl::type_decl(const std::string&	name,
 {
 }
 
+/// Get a singleton representing a void type node.
+///
+/// @return the void type node.
+type_decl_sptr
+type_decl::get_void_type_decl()
+{
+  static type_decl_sptr void_type_decl;
+  if (!void_type_decl)
+    void_type_decl.reset(new type_decl("void", 0, 0, location()));
+  return void_type_decl;
+}
+
 /// Return true if both types equals.
 ///
 /// This operator re-uses the overload that takes a decl_base.

tests/Makefile.am

@@ -177,6 +177,10 @@ tests/data/test-read-dwarf/test2.so		\
 tests/data/test-read-dwarf/test2.so.abi		\
 tests/data/test-read-dwarf/test3.c		\
 tests/data/test-read-dwarf/test3.so		\
+tests/data/test-read-dwarf/test4.c		\
+tests/data/test-read-dwarf/test4.so		\
+tests/data/test-read-dwarf/test5.cc		\
+tests/data/test-read-dwarf/test5.so		\
 \
 data/test-diff-filter/test0-v0.cc		\
 data/test-diff-filter/test0-v1.cc		\

tests/data/test-read-dwarf/test5.cc

@@ -0,0 +1,6 @@
+/// Compile this by doing g++ -g -Wall -c test5.cc
+
+void
+bar(void*)
+{
+}

tests/data/test-read-dwarf/test5.o.abi

@@ -0,0 +1,12 @@
+<abi-corpus path='data/test-read-dwarf/test5.o'>
+  <elf-function-symbols>
+    <elf-symbol name='_Z3barPv' type='func-type' binding='global-binding' is-defined='yes'/>
+  </elf-function-symbols>
+  <abi-instr version='1.0' address-size='64' path='test.cc'>
+    <type-decl name='void' id='type-id-1'/>
+    <pointer-type-def type-id='type-id-1' size-in-bits='64' alignment-in-bits='64' id='type-id-2'/>
+    <function-decl name='bar' mangled-name='_Z3barPv' filepath='/home/dodji/libabigailtests/test.cc' line='2' column='1' visibility='default' binding='global' size-in-bits='64' alignment-in-bits='64' elf-symbol-id='_Z3barPv'>
+      <parameter type-id='type-id-2'/>
+    </function-decl>
+  </abi-instr>
+</abi-corpus>

tests/test-read-dwarf.cc

@@ -75,6 +75,11 @@ InOutSpec in_out_specs[] =
     "data/test-read-dwarf/test4.so.abi",
     "output/test-read-dwarf/test4.so.abi"
   },
+  {
+    "data/test-read-dwarf/test5.o",
+    "data/test-read-dwarf/test5.o.abi",
+    "output/test-read-dwarf/test5.o.abi"
+  },
   // This should be the last entry.
   {NULL, NULL, NULL}
 };