[binutils-gdb] [gdb] Fix build breaker with gcc 4.8

[binutils-gdb] [gdb] Fix build breaker with gcc 4.8

[Tom de Vries]

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f23f598e28ad39dac7ae87cdc400d2f6b27dc403

commit f23f598e28ad39dac7ae87cdc400d2f6b27dc403
Author: Tom de Vries <tdevries@suse.de>
Date:   Wed Jun 19 16:56:23 2019 +0200

    [gdb] Fix build breaker with gcc 4.8
    
    When compiling with gcc 4.8, we run into:
    ...
    /usr/include/c++/4.8/bits/unordered_map.h:100:18: required from \
      ‘class std::unordered_map<sect_offset, std::vector<sect_offset> >’
    src/gdb/dwarf2read.h:260:5:   required from here
    /usr/include/c++/4.8/bits/hashtable_policy.h:1070:12: error: invalid use of \
      incomplete type ‘struct std::hash<sect_offset>’
    ...
    
    Fix this by setting the Hash template parameter of the unordered_map to
    gdb::hash_enum<sect_offset>, rather than using the default
    std::hash<sect_offset>.
    
    Build and reg-tested on x86_64-linux with gcc 4.8.
    
    gdb/ChangeLog:
    
    2019-06-19  Tom de Vries  <tdevries@suse.de>
    
    	* dwarf2read.h (abstract_to_concrete): Change type to
    	std::unordered_map<sect_offset, std::vector<sect_offset>,
    	gdb::hash_enum<sect_offset>>.

Diff:
---
 gdb/ChangeLog    | 6 ++++++
 gdb/dwarf2read.h | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index c40b7d4..0937823 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2019-06-19  Tom de Vries  <tdevries@suse.de>
+
+	* dwarf2read.h (abstract_to_concrete): Change type to
+	std::unordered_map<sect_offset, std::vector<sect_offset>,
+	gdb::hash_enum<sect_offset>>.
+
 2019-06-19  Tom Tromey  <tromey@adacore.com>
 
 	* ada-lang.c (ada_evaluate_subexp) <case OP_ATR_FIRST>: Handle
diff --git a/gdb/dwarf2read.h b/gdb/dwarf2read.h
index 776860e..7113cfd 100644
--- a/gdb/dwarf2read.h
+++ b/gdb/dwarf2read.h
@@ -24,6 +24,7 @@
 #include "dwarf-index-cache.h"
 #include "filename-seen-cache.h"
 #include "gdb_obstack.h"
+#include "common/hash_enum.h"
 
 /* Hold 'maintenance (set|show) dwarf' commands.  */
 extern struct cmd_list_element *set_dwarf_cmdlist;
@@ -256,7 +257,8 @@ public:
 
   /* Mapping from abstract origin DIE to concrete DIEs that reference it as
      DW_AT_abstract_origin.  */
-  std::unordered_map<sect_offset, std::vector<sect_offset>>
+  std::unordered_map<sect_offset, std::vector<sect_offset>, \
+		     gdb::hash_enum<sect_offset>> \
     abstract_to_concrete;
 };