[patchv2] compile: Fix crash on cv-qualified self-reference

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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On Sat, 18 Apr 2015 19:28:43 +0200, Jan Kratochvil wrote:
Hi,

with this modified testcase GDB would:

compile code struct_object.selffield = &struct_object
./compile/compile-c-types.c:83: internal-error: insert_type: Assertion `add == NULL || add->gcc_type == gcc_type' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) FAIL: gdb.compile/compile.exp: compile code struct_object.selffield = &struct_object (GDB internal error)

While the insert_type() assertion looks unclear trying to fix it one ends up
with either GCC crash
	[gcc libcc1] build_qualified_type for self-referencing/incomplete types
	https://gcc.gnu.org/ml/gcc/2015-04/msg00108.html
	c_incomplete_type_error()
or after fixing up the GCC type for proper error reporting one gets:
	gdb command line:1:1: error: invalid use of incomplete typedef ‘sv’
which is the real culprit of this bug as explained in this patch.

This patch is related to the XFAIL introduced by
	[PATCH v3 5/9] compile: Use -Wall, not -w
	https://sourceware.org/ml/gdb-patches/2015-04/msg00429.html
as for proper -Wall happiness the 'volatile' qualifier needs to be added there
- but adding the qualifier has caused this crash.

No regressions on {x86_64,x86_64-m32,i686}-fedora23pre-linux-gnu.


Thanks,
Jan

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gdb/ChangeLog
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	compile: Fix crash on cv-qualified self-reference.
	* compile/compile-c-types.c (convert_struct_or_union): Apply
	build_qualified_type.
	(convert_type_basic): Do not apply build_qualified_type for
	TYPE_CODE_STRUCT and TYPE_CODE_UNION.

gdb/testsuite/ChangeLog
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	compile: Fix crash on cv-qualified self-reference.
	* gdb.compile/compile.c (struct struct_type): Add volatile for
	selffield.
	* gdb.compile/compile.exp
	(compile code struct_object.selffield = &struct_object): Remove XFAIL.

diff --git a/gdb/compile/compile-c-types.c b/gdb/compile/compile-c-types.c
index 2b521bc..420f61d 100644
--- a/gdb/compile/compile-c-types.c
+++ b/gdb/compile/compile-c-types.c
@@ -166,9 +166,13 @@ convert_struct_or_union (struct compile_c_instance *context, struct type *type)
 {
   int i;
   gcc_type result;
+  int quals;
 
   /* First we create the resulting type and enter it into our hash
-     table.  This lets recursive types work.  */
+     table.  This lets recursive types work.  We have to create gcc_type
+     already with its qualifiers to prevent recursively calling
+     build_qualified_type for unfinished TYPE as build_qualified_type
+     creates a copy of the type, remaining unfinished forever.  */
   if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
     result = C_CTX (context)->c_ops->build_record_type (C_CTX (context));
   else
@@ -176,6 +180,15 @@ convert_struct_or_union (struct compile_c_instance *context, struct type *type)
       gdb_assert (TYPE_CODE (type) == TYPE_CODE_UNION);
       result = C_CTX (context)->c_ops->build_union_type (C_CTX (context));
     }
+  quals = 0;
+  if (TYPE_CONST (type))
+    quals |= GCC_QUALIFIER_CONST;
+  if (TYPE_VOLATILE (type))
+    quals |= GCC_QUALIFIER_VOLATILE;
+  if (TYPE_RESTRICT (type))
+    quals |= GCC_QUALIFIER_RESTRICT;
+  result = C_CTX (context)->c_ops->build_qualified_type (C_CTX (context),
+							 result, quals);
   insert_type (context, type, result);
 
   for (i = 0; i < TYPE_NFIELDS (type); ++i)
@@ -329,10 +342,13 @@ static gcc_type
 convert_type_basic (struct compile_c_instance *context, struct type *type)
 {
   /* If we are converting a qualified type, first convert the
-     unqualified type and then apply the qualifiers.  */
+     unqualified type and then apply the qualifiers, except for the
+     types handling qualifiers on their own.  */
   if ((TYPE_INSTANCE_FLAGS (type) & (TYPE_INSTANCE_FLAG_CONST
 				     | TYPE_INSTANCE_FLAG_VOLATILE
-				     | TYPE_INSTANCE_FLAG_RESTRICT)) != 0)
+				     | TYPE_INSTANCE_FLAG_RESTRICT)) != 0
+      && (TYPE_CODE (type) != TYPE_CODE_STRUCT
+	  && TYPE_CODE (type) != TYPE_CODE_UNION))
     return convert_qualified (context, type);
 
   switch (TYPE_CODE (type))
diff --git a/gdb/testsuite/gdb.compile/compile.c b/gdb/testsuite/gdb.compile/compile.c
index 3d5f20a..41ff087 100644
--- a/gdb/testsuite/gdb.compile/compile.c
+++ b/gdb/testsuite/gdb.compile/compile.c
@@ -42,7 +42,7 @@ struct struct_type {
   float floatfield;
   double doublefield;
   const union union_type *ptrfield;
-  struct struct_type *selffield;
+  volatile struct struct_type *selffield;
   int arrayfield[5];
   _Complex double complexfield;
   _Bool boolfield;
diff --git a/gdb/testsuite/gdb.compile/compile.exp b/gdb/testsuite/gdb.compile/compile.exp
index 07276bd..9668be8 100644
--- a/gdb/testsuite/gdb.compile/compile.exp
+++ b/gdb/testsuite/gdb.compile/compile.exp
@@ -189,15 +189,7 @@ gdb_test "p localvar" " = 1"
 # Test setting fields and also many different types.
 #
 
-set test "compile code struct_object.selffield = &struct_object"
-gdb_test_multiple $test $test {
-    -re "^$test\r\n$gdb_prompt $" {
-	pass "$test"
-    }
-    -re "gdb command line:1:25: warning: assignment discards 'volatile' qualifier from pointer target type \\\[-Wdiscarded-qualifiers\\\]\r\n$gdb_prompt $" {
-	xfail "$test (PR compile/18202)"
-    }
-}
+gdb_test_no_output "compile code struct_object.selffield = &struct_object"
 gdb_test "print struct_object.selffield == &struct_object" " = 1"
 
 gdb_test_no_output "compile code struct_object.charfield = 1"