[PATCH] Fix windows-nat.c for -Wnarrowing

[Tom Tromey <tom@tromey.com>]

Sergio pointed out that the Windows builder was failing due to the
-Wnarrowing patch, with:

../../binutils-gdb/gdb/windows-nat.c:301:27: error: narrowing conversion of '3221225477' from 'DWORD {aka long unsigned int}' to 'int' inside { } [-Wnarrowing]
   {-1, GDB_SIGNAL_UNKNOWN}};
                           ^
../../binutils-gdb/gdb/windows-nat.c:301:27: error: narrowing conversion of '3221225725' from 'DWORD {aka long unsigned int}' to 'int' inside { } [-Wnarrowing]
../../binutils-gdb/gdb/windows-nat.c:301:27: error: narrowing conversion of '2147483651' from 'DWORD {aka long unsigned int}' to 'int' inside { } [-Wnarrowing]
../../binutils-gdb/gdb/windows-nat.c:301:27: error: narrowing conversion of '2147483652' from 'DWORD {aka long unsigned int}' to 'int' inside { } [-Wnarrowing]
../../binutils-gdb/gdb/windows-nat.c:301:27: error: narrowing conversion of '3221225614' from 'DWORD {aka long unsigned int}' to 'int' inside { } [-Wnarrowing]

Looking into this, I found two things.

First, in struct xlate_exception, it is better to have "them" be of
type DWORD, as that's the type actually in use.

Second, struct xlate_exception and xlate are not used in this file,
because the code in windows_nat_target::resume is #if'd out.

This patch changes the type of "them", but also similarly #if's out
this object.

Tested by rebuilding using the mingw toolchain on x86-64 Fedora 28.

gdb/ChangeLog
2018-08-29  Tom Tromey  <tom@tromey.com>

	* windows-nat.c (struct xlate_exception) <them>: Change type to
	DWORD.
	(xlate): Fix formatting.
	(struct xlate_exception, xlate): Comment out.
---
 gdb/ChangeLog     |  7 +++++++
 gdb/windows-nat.c | 12 ++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a30dacee4a3..0c4327f0637 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2018-08-29  Tom Tromey  <tom@tromey.com>
+
+	* windows-nat.c (struct xlate_exception) <them>: Change type to
+	DWORD.
+	(xlate): Fix formatting.
+	(struct xlate_exception, xlate): Comment out.
+
 2018-08-29  Sergio Durigan Junior  <sergiodj@redhat.com>
 
 	PR gdb/23555
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index aea502638e0..404646c94b0 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -280,17 +280,19 @@ static const int *mappings;
    a segment register or not.  */
 static segment_register_p_ftype *segment_register_p;
 
+/* See windows_nat_target::resume to understand why this is commented
+   out.  */
+#if 0
 /* This vector maps the target's idea of an exception (extracted
    from the DEBUG_EVENT structure) to GDB's idea.  */
 
 struct xlate_exception
   {
-    int them;
+    DWORD them;
     enum gdb_signal us;
   };
 
-static const struct xlate_exception
-  xlate[] =
+static const struct xlate_exception xlate[] =
 {
   {EXCEPTION_ACCESS_VIOLATION, GDB_SIGNAL_SEGV},
   {STATUS_STACK_OVERFLOW, GDB_SIGNAL_SEGV},
@@ -298,8 +300,10 @@ static const struct xlate_exception
   {DBG_CONTROL_C, GDB_SIGNAL_INT},
   {EXCEPTION_SINGLE_STEP, GDB_SIGNAL_TRAP},
   {STATUS_FLOAT_DIVIDE_BY_ZERO, GDB_SIGNAL_FPE},
-  {-1, GDB_SIGNAL_UNKNOWN}};
+  {-1, GDB_SIGNAL_UNKNOWN}
+};
 
+#endif /* 0 */
 
 struct windows_nat_target final : public x86_nat_target<inf_child_target>
 {
-- 
2.17.1