[review] Don't use class-initialization for the owner union

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/684
......................................................................

Don't use class-initialization for the owner union

As reported by PhilippeW, valgrind reports that symtab is uninitialized
when compiling with GCC 4.8.5, which is the default compiler on CentOS 7.

This is apparently a compiler bug fixed in later versions, but to keep
CentOS 7 working, this patch initializes the union explicitly instead of
using a class initializer.

gdb/ChangeLog:

2019-11-17  Christian Biesinger  <cbiesinger@google.com>

	* symtab.h (struct symbol) <owner>: Initialize explicitly in the
	constructor instead of using a class initializer.

Change-Id: I94f48afeae5d29cf81a280295e2d02e2d7e1c1f1
---
M gdb/symtab.h
1 file changed, 4 insertions(+), 1 deletion(-)



diff --git a/gdb/symtab.h b/gdb/symtab.h
index a6bd3c4..1e82182 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -1113,6 +1113,9 @@
       language = language_unknown;
       ada_mangled = 0;
       section = 0;
+      /* GCC 4.8.5 (on CentOS 7) does not correctly compile class-
+         initialization of unions, so we initialize it manually here.  */
+      owner.symtab = nullptr;
     }
 
   /* Data type of value */
@@ -1127,7 +1130,7 @@
     /* The symbol table containing this symbol.  This is the file associated
        with LINE.  It can be NULL during symbols read-in but it is never NULL
        during normal operation.  */
-    struct symtab *symtab = nullptr;
+    struct symtab *symtab;
 
     /* For types defined by the architecture.  */
     struct gdbarch *arch;

-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: I94f48afeae5d29cf81a280295e2d02e2d7e1c1f1
Gerrit-Change-Number: 684
Gerrit-PatchSet: 1
Gerrit-Owner: Christian Biesinger <cbiesinger@google.com>
Gerrit-MessageType: newchange