gdb: Silence -Wformat-nonliteral warning with clang

Message ID 20191011205426.1859-1-simon.marchi@efficios.com
State New
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Series
  • gdb: Silence -Wformat-nonliteral warning with clang
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Commit Message

Simon Marchi Oct. 11, 2019, 8:54 p.m.
We get this warning when building with clang:

      CXX    ui-out.o
    /home/smarchi/src/binutils-gdb/gdb/ui-out.c:590:22: error: format string is not a string literal [-Werror,-Wformat-nonliteral]
      do_message (style, format, args);
                         ^~~~~~

This can be considered a legitimate warning, as call_do_message's format
parameter is not marked as a format string.  Therefore, we should
normally mark the call_do_message method with the `format` attribute.
However, doing so just moves (and multiplies) the problem, as all the
uses of call_do_message in the vmessage method now warn.  If we wanted
to continue on that path, we should silence the warning for each of
them, as a way of telling the compiler "it's ok, we know what we are
doing".

But since call_do_message is really just vmessage's little helper, it's
simpler to just silence the warning at that single point.

gdb/ChangeLog:

	* ui-out.c (ui_out::call_do_message): Silence
	-Wformat-nonliteral warning.

Change-Id: I58ad41793448f38835c5d6ba7b9e5c4dd8df260f
---
 gdb/ui-out.c | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.23.0

Comments

Kevin Buettner Oct. 13, 2019, 6:17 p.m. | #1
On Fri, 11 Oct 2019 16:54:26 -0400
Simon Marchi <simon.marchi@efficios.com> wrote:

> We get this warning when building with clang:

> 

>       CXX    ui-out.o

>     /home/smarchi/src/binutils-gdb/gdb/ui-out.c:590:22: error: format string is not a string literal [-Werror,-Wformat-nonliteral]

>       do_message (style, format, args);

>                          ^~~~~~

> 

> This can be considered a legitimate warning, as call_do_message's format

> parameter is not marked as a format string.  Therefore, we should

> normally mark the call_do_message method with the `format` attribute.

> However, doing so just moves (and multiplies) the problem, as all the

> uses of call_do_message in the vmessage method now warn.  If we wanted

> to continue on that path, we should silence the warning for each of

> them, as a way of telling the compiler "it's ok, we know what we are

> doing".

> 

> But since call_do_message is really just vmessage's little helper, it's

> simpler to just silence the warning at that single point.

> 

> gdb/ChangeLog:

> 

> 	* ui-out.c (ui_out::call_do_message): Silence

> 	-Wformat-nonliteral warning.


LGTM.

Kevin
Simon Marchi Oct. 14, 2019, midnight | #2
On 2019-10-13 14:17, Kevin Buettner wrote:
> On Fri, 11 Oct 2019 16:54:26 -0400

> Simon Marchi <simon.marchi@efficios.com> wrote:

> 

>> We get this warning when building with clang:

>> 

>>       CXX    ui-out.o

>>     /home/smarchi/src/binutils-gdb/gdb/ui-out.c:590:22: error: format 

>> string is not a string literal [-Werror,-Wformat-nonliteral]

>>       do_message (style, format, args);

>>                          ^~~~~~

>> 

>> This can be considered a legitimate warning, as call_do_message's 

>> format

>> parameter is not marked as a format string.  Therefore, we should

>> normally mark the call_do_message method with the `format` attribute.

>> However, doing so just moves (and multiplies) the problem, as all the

>> uses of call_do_message in the vmessage method now warn.  If we wanted

>> to continue on that path, we should silence the warning for each of

>> them, as a way of telling the compiler "it's ok, we know what we are

>> doing".

>> 

>> But since call_do_message is really just vmessage's little helper, 

>> it's

>> simpler to just silence the warning at that single point.

>> 

>> gdb/ChangeLog:

>> 

>> 	* ui-out.c (ui_out::call_do_message): Silence

>> 	-Wformat-nonliteral warning.

> 

> LGTM.

> 

> Kevin


Thanks, I pushed it.

Simon

Patch

diff --git a/gdb/ui-out.c b/gdb/ui-out.c
index a64c79481cad..6b0b5acd3e13 100644
--- a/gdb/ui-out.c
+++ b/gdb/ui-out.c
@@ -26,6 +26,7 @@ 
 #include "ui-out.h"
 #include "gdbsupport/format.h"
 #include "cli/cli-style.h"
+#include "diagnostics.h"
 
 #include <vector>
 #include <memory>
@@ -587,7 +588,15 @@  ui_out::call_do_message (const ui_file_style &style, const char *format,
   va_list args;
 
   va_start (args, format);
+
+  /* Since call_do_message is only used as a helper of vmessage, silence the
+     warning here once instead of at all call sites in vmessage, if we were
+     to put a "format" attribute on call_do_message.  */
+  DIAGNOSTIC_PUSH
+  DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL
   do_message (style, format, args);
+  DIAGNOSTIC_POP
+
   va_end (args);
 }