[pushed] Handle complex error type in read_base_type

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[pushed] Handle complex error type in read_base_type

Tom Tromey-4
It turns out there was one more bug in the earlier complex series:
read_base_type could cause an assertion failure on some platforms.  I
found this running the AdaCore internal test suite, but you can also
see it by running gdb's "gdb.cp" tests for x86 (not x86-64).

In particular, the DW_ATE_complex_float case calls
dwarf2_init_complex_target_type, which calls dwarf2_init_float_type,
which can return a type using TYPE_CODE_ERROR.

This patch changes the DWARF reader to handle this case, the same way
that the f-lang.c patch did.  Perhaps init_complex_type really should
be changed to allow TYPE_CODE_ERROR?  I was not sure.

Tested on x86-64 Fedora 30, using an x86 build.  I'm checking this in.

gdb/ChangeLog
2020-04-06  Tom Tromey  <[hidden email]>

        * dwarf2/read.c (read_base_type) <DW_ATE_complex_float>: Handle
        TYPE_CODE_ERROR.
---
 gdb/ChangeLog     |  5 +++++
 gdb/dwarf2/read.c | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index bcc3116071e..749acb3ba26 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -16910,7 +16910,19 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
       case DW_ATE_complex_float:
  type = dwarf2_init_complex_target_type (cu, objfile, bits / 2, name,
  byte_order);
- type = init_complex_type (name, type);
+ if (TYPE_CODE (type) == TYPE_CODE_ERROR)
+  {
+    if (name == nullptr)
+      {
+ struct obstack *obstack
+  = &cu->per_cu->dwarf2_per_objfile->objfile->objfile_obstack;
+ name = obconcat (obstack, "_Complex ", TYPE_NAME (type),
+ nullptr);
+      }
+    type = init_type (objfile, TYPE_CODE_ERROR, bits, name);
+  }
+ else
+  type = init_complex_type (name, type);
  break;
       case DW_ATE_decimal_float:
  type = init_decfloat_type (objfile, bits, name);
--
2.21.1