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:

2019-11-18  Christian Biesinger  <cbiesinger@google.com>

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

Change-Id: I94f48afeae5d29cf81a280295e2d02e2d7e1c1f1

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 90a2b64d3df2470e71e95033c4b9f0818f0f3c32..0e17d7c39d86b0fe8f6a1ed9d8753e4d18fc9643 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-18  Christian Biesinger  <cbiesinger@google.com>
+
+       * symtab.h (struct symbol) <owner>: Initialize explicitly in the
+       constructor instead of using a class initializer.
+
 2019-11-15  Christian Biesinger  <cbiesinger@google.com>
 
        * Makefile.in: Replace {posix,mingw}-strerror.c with safe-strerror.c.

diff --git a/gdb/symtab.h b/gdb/symtab.h
index a6bd3c44b806fd323b79c5452d3153ac443f96af..1e82182df793d77a0ca7e30385ce5c73a4681d47 100644 (file)
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -1113,6 +1113,9 @@ struct symbol : public general_symbol_info, public allocate_on_obstack
       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 @@ struct symbol : public general_symbol_info, public allocate_on_obstack
     /* 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;