In Visual C++, it's possible to use #pragma warning (disable: ...). Also I found that in GCC you can override per file compiler flags. How can I do this for "next line", or with push/pop semantics around areas of code using GCC?
It appears this can be done. I'm unable to determine the version of GCC that it was added, but it was sometime before June 2010.
Here's an example:
#pragma GCC diagnostic error "-Wuninitialized"
foo(a); /* error is given for this one */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wuninitialized"
foo(b); /* no diagnostic for this one */
#pragma GCC diagnostic pop
foo(c); /* error is given for this one */
#pragma GCC diagnostic pop
foo(d); /* depends on command line options */
To net everything out, this is an example of temporarily disabling a warning:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-result"
write(foo, bar, baz);
#pragma GCC diagnostic pop
You can check the GCC documentation on diagnostic pragmas for more details.
TL;DR: If it works, avoid, or use specifiers like _Noreturn, [[nodiscard]], __attribute__, otherwise _Pragma.
This is a short version of my blog article
Suppressing Warnings in GCC and Clang.
Consider the following Makefile,
CPPFLAGS:=-std=c11 -W -Wall -pedantic -Werror
.PHONY: all
all: puts
for building the following puts.c source code:
#include <stdio.h>
int main(int argc, const char *argv[])
{
while (*++argv)
puts(*argv);
return 0;
}
It will not compile because argc is unused, and the settings are hardcore (-W -Wall -pedantic -Werror).
There are five things you could do:
Improve the source code, if possible
Use an attribute, like [[maybe_unused]]
Use a declaration specifier, like __attribute__
Use _Pragma
Use #pragma
Use a command line option.
Improving the source
The first attempt should be checking if the source code can be improved to get rid of the warning. In this case we don't want to change the algorithm just because of that, as argc is redundant with !*argv (NULL after last element).
Using an attribute, like [[maybe_unused]]
#include <stdio.h>
int main([[maybe_unused]] int argc, const char *argv[])
{
while (*++argv) puts(*argv);
return 0;
}
If you're lucky, the standard provides an attribute for your situation, like [[maybe_unused]]. Attributes are a new feature of C2x. So far, C2x defines four attributes, [[deprecated]], [[fallthrough]], [[maybe_unused]], and [[nodiscard]].
Using a declaration specifier, like __attribute__
#include <stdio.h>
int main(__attribute__((unused)) int argc, const char *argv[])
{
while (*++argv) puts(*argv);
return 0;
}
If you're lucky, the standard provides a specifier for your situation, like _Noreturn.
__attribute__ is proprietary GCC extension (supported by Clang and some other compilers like armcc as well) and will not be understood by many other compilers. Put __attribute__((unused)) inside a macro if you want portable code.
_Pragma operator
_Pragma can be used as an alternative to #pragma.
#include <stdio.h>
_Pragma("GCC diagnostic push")
_Pragma("GCC diagnostic ignored \"-Wunused-parameter\"")
int main(int argc, const char *argv[])
{
while (*++argv)
puts(*argv);
return 0;
}
_Pragma("GCC diagnostic pop")
The main advantage of the _Pragma operator is that you could put it inside macros, which is not possible with the #pragma directive.
Downside: It's almost a tactical nuke, as it works line-based instead of declaration-based.
The _Pragma operator was introduced in C99.
#pragma directive.
We could change the source code to suppress the warning for a region of code, typically an entire function:
#include <stdio.h>
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
int main(int argc, const char *argv[])
{
while (*++argc) puts(*argv);
return 0;
}
#pragma GCC diagnostic pop
Downside: It's almost a tactical nuke, as it works line-based instead of declaration-based.
Note that a similar syntax exists in Clang.
Suppressing the warning on the command line for a single file
We could add the following line to the Makefile to suppress the warning specifically for puts:
CPPFLAGS:=-std=c11 -W -Wall -pedantic -Werror
.PHONY: all
all: puts
puts.o: CPPFLAGS+=-Wno-unused-parameter
This is probably not want you want in your particular case, but it may help other readers who are in similar situations.
I know the question is about GCC, but for people looking for how to do this in other and/or multiple compilers…
TL;DR
You might want to take a look at Hedley, which is a public-domain single C/C++ header I wrote which does a lot of this stuff for you. I'll put a quick section about how to use Hedley for all this at the end of this post.
Disabling the warning
#pragma warning (disable: …) has equivalents in most compilers:
MSVC: #pragma warning(disable:4996)
GCC: #pragma GCC diagnostic ignored "-W…" where the ellipsis is the name of the warning; e.g., #pragma GCC diagnostic ignored "-Wdeprecated-declarations.
Clang: #pragma clang diagnostic ignored "-W…". The syntax is basically the same as GCC's, and many of the warning names are the same (though many aren't).
Intel C++ Compiler (ICC): Use the MSVC syntax, but keep in mind that warning numbers are totally different. Example: #pragma warning(disable:1478 1786).
PGI/Nvidia: There is a diag_suppress pragma: #pragma diag_suppress 1215,1444. Note that all warning numbers increased by one in 20.7 (the first Nvidia HPC release).
TI (CCS): There is a diag_suppress pragma with the same syntax (but different warning numbers!) as PGI: pragma diag_suppress 1291,1718
Oracle Developer Studio (ODS) (suncc): there is an error_messages pragma. Annoyingly, the warnings are different for the C and C++ compilers. Both of these disable basically the same warnings:
C: #pragma error_messages(off,E_DEPRECATED_ATT,E_DEPRECATED_ATT_MESS)
C++: #pragma error_messages(off,symdeprecated,symdeprecated2)
IAR: also uses diag_suppress like PGI and TI, but the syntax is different. Some of the warning numbers are the same, but I others have diverged: #pragma diag_suppress=Pe1444,Pe1215
Pelles C: similar to MSVC, though again the numbers are different #pragma warn(disable:2241)
For most compilers it is often a good idea to check the compiler version before trying to disable it, otherwise you'll just end up triggering another warning. For example, GCC 7 added support for the -Wimplicit-fallthrough warning, so if you care about GCC before 7 you should do something like
#if defined(__GNUC__) && (__GNUC__ >= 7)
# pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
#endif
For Clang and compilers based on Clang, such as newer versions of XL C/C++ and armclang, you can check to see if the compiler knows about a particular warning using the __has_warning() macro.
#if __has_warning("-Wimplicit-fallthrough")
# pragma clang diagnostic ignored "-Wimplicit-fallthrough"
#endif
Of course you also have to check to see if the __has_warning() macro exists:
#if defined(__has_warning)
# if __has_warning("-Wimplicit-fallthrough")
# pragma clang diagnostic ignored "-Wimplicit-fallthrough"
# endif
#endif
You may be tempted to do something like
#if !defined(__has_warning)
# define __has_warning(warning)
#endif
So you can use __has_warning a bit more easily. Clang even suggests something similar for the __has_builtin() macro in their manual. Do not do this. Other code may check for __has_warning and fall back on checking compiler versions if it doesn't exist, and if you define __has_warning you'll break their code. The right way to do this is to create a macro in your namespace. For example:
#if defined(__has_warning)
# define MY_HAS_WARNING(warning) __has_warning(warning)
#else
# define MY_HAS_WARNING(warning) (0)
#endif
Then you can do stuff like
#if MY_HAS_WARNING(warning)
# pragma clang diagnostic ignored "-Wimplicit-fallthrough"
#elif defined(__GNUC__) && (__GNUC__ >= 7)
# pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
#endif
Pushing and popping
Many compilers also support a way to push and pop warnings onto a stack. For example, this will disable a warning on GCC for one line of code, then return it to its previous state:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated"
call_deprecated_function();
#pragma GCC diagnostic pop
Of course there isn't a lot of agreement across compilers about the syntax:
GCC 4.6+: #pragma GCC diagnostic push / #pragma GCC diagnostic pop
Clang: #pragma clang diagnostic push / #pragma clang diagnostic pop
Intel 13+ (and probably earlier): #pragma warning(push) / #pragma warning(pop)
MSVC 15+ (Visual Studio 9.0 / 2008): #pragma warning(push) / #pragma warning(pop)
ARM 5.6+: #pragma push / #pragma pop
TI 8.1+: #pragma diag_push / #pragma diag_pop
Pelles C 2.90+ (and probably earlier): #pragma warning(push) / #pragma warning(pop)
If memory serves, for some very old versions of GCC (like 3.x, IIRC) the push/pop pragmas had to be outside of the function.
Hiding the gory details
For most compilers it's possible to hide the logic behind macros using _Pragma, which was introduced in C99. Even in non-C99 mode, most compilers support _Pragma; the big exception is MSVC, which has its own __pragma keyword with a different syntax. The standard _Pragma takes a string, Microsoft's version doesn't:
#if defined(_MSC_VER)
# define PRAGMA_FOO __pragma(foo)
#else
# define PRAGMA_FOO _Pragma("foo")
#endif
PRAGMA_FOO
Is roughly equivalent, once preprocessed, to
#pragma foo
This let’s us create macros so we can write code like
MY_DIAGNOSTIC_PUSH
MY_DIAGNOSTIC_DISABLE_DEPRECATED
call_deprecated_function();
MY_DIAGNOSTIC_POP
And hide away all the ugly version checks in the macro definitions.
The easy way: Hedley
Now that you understand the mechanics of how to do stuff like this portably while keeping your code clean, you understand what one of my projects, Hedley does. Instead of digging through tons of documentation and/or installing as many versions of as many compilers as you can to test with, you can just include Hedley (it is a single public domain C/C++ header) and be done with it. For example:
#include "hedley.h"
HEDLEY_DIAGNOSTIC_PUSH
HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
call_deprecated();
HEDLEY_DIAGNOSTIC_POP
Will disable the warning about calling a deprecated function on GCC, Clang, ICC, PGI, MSVC, TI, IAR, ODS, Pelles C, and possibly others (I probably won't bother updating this answer as I update Hedley). And, on compilers which aren't known to work, the macros will be preprocessed away to nothing, so your code will continue to work with any compiler. Of course HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED isn't the only warning Hedley knows about, nor is disabling warnings all Hedley can do, but hopefully you get the idea.
#pragma GCC diagnostic ignored "-Wformat"
Replace "-Wformat" with the name of your warning flag.
AFAIK there is no way to use push/pop semantics for this option.
Use:
#define DIAG_STR(s) #s
#define DIAG_JOINSTR(x,y) DIAG_STR(x ## y)
#ifdef _MSC_VER
#define DIAG_DO_PRAGMA(x) __pragma (#x)
#define DIAG_PRAGMA(compiler,x) DIAG_DO_PRAGMA(warning(x))
#else
#define DIAG_DO_PRAGMA(x) _Pragma (#x)
#define DIAG_PRAGMA(compiler,x) DIAG_DO_PRAGMA(compiler diagnostic x)
#endif
#if defined(__clang__)
# define DISABLE_WARNING(gcc_unused,clang_option,msvc_unused) DIAG_PRAGMA(clang,push) DIAG_PRAGMA(clang,ignored DIAG_JOINSTR(-W,clang_option))
# define ENABLE_WARNING(gcc_unused,clang_option,msvc_unused) DIAG_PRAGMA(clang,pop)
#elif defined(_MSC_VER)
# define DISABLE_WARNING(gcc_unused,clang_unused,msvc_errorcode) DIAG_PRAGMA(msvc,push) DIAG_DO_PRAGMA(warning(disable:##msvc_errorcode))
# define ENABLE_WARNING(gcc_unused,clang_unused,msvc_errorcode) DIAG_PRAGMA(msvc,pop)
#elif defined(__GNUC__)
#if ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406
# define DISABLE_WARNING(gcc_option,clang_unused,msvc_unused) DIAG_PRAGMA(GCC,push) DIAG_PRAGMA(GCC,ignored DIAG_JOINSTR(-W,gcc_option))
# define ENABLE_WARNING(gcc_option,clang_unused,msvc_unused) DIAG_PRAGMA(GCC,pop)
#else
# define DISABLE_WARNING(gcc_option,clang_unused,msvc_unused) DIAG_PRAGMA(GCC,ignored DIAG_JOINSTR(-W,gcc_option))
# define ENABLE_WARNING(gcc_option,clang_option,msvc_unused) DIAG_PRAGMA(GCC,warning DIAG_JOINSTR(-W,gcc_option))
#endif
#endif
This should do the trick for GCC, Clang and MSVC.
It can be called with e.g.:
DISABLE_WARNING(unused-variable,unused-variable,42)
[.... some code with warnings in here ....]
ENABLE_WARNING(unused-variable,unused-variable,42)
See 7 Pragmas, Controlling Diagnostics via Pragmas and Pragma directives and the __pragma and _Pragma keywords for more details.
You need at least version 4.02 to use these kind of pragmas for GCC, and I am not sure about MSVC and Clang about the versions.
It looks like the push pop pragma handling for GCC is a little bit broken. If you enable the warning again, you still get the warning for the block that was inside the DISABLE_WARNING/ENABLE_WARNING block. For some versions of GCC it works, and for some it doesn't.
I had same issue with external libraries like ROS headers. I like to use following options in CMakeLists.txt for stricter compilation:
set(CMAKE_CXX_FLAGS "-std=c++0x -Wall -Wextra -Wstrict-aliasing -pedantic -Werror -Wunreachable-code ${CMAKE_CXX_FLAGS}")
However, doing this causes all kind of pedantic errors in externally included libraries as well. The solution is to disable all pedantic warnings before you include external libraries and re-enable them like this:
// Save compiler switches
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
// Bad headers with a problem goes here
#include <ros/ros.h>
#include <sensor_msgs/LaserScan.h>
// Restore compiler switches
#pragma GCC diagnostic pop
Rather than silencing the warnings, GCC style is usually to use either standard C constructs or the __attribute__ extension to tell the compiler more about your intention.
For instance, the warning about assignment used as a condition is suppressed by putting the assignment in parentheses, i.e. if ((p=malloc(cnt))) instead of if (p=malloc(cnt)).
Warnings about unused function arguments can be suppressed by some odd __attribute__ I can never remember, or by self-assignment, etc.
But generally I prefer just globally disabling any warning option that generates warnings for things that will occur in correct code.
Here is a way to do this in IAR. Try this:
#pragma diag_suppress=Pe177
void foo1(void)
{
/* The following line of code would normally provoke diagnostic
message #177-D: variable "x" was declared but never referenced.
Instead, we have suppressed this warning throughout the entire
scope of foo1().
*/
int x;
}
#pragma diag_default=Pe177
See official documentation for reference.
I have a C single-header library that I would like to use in my C++ project. Normally, I would just include the file and that would be fine because C++ is almost a superset of C. However, this library has a goto that jumps over an initialization, violating the C++ standard.
I can get around this be enabling the -fpermissive compiler flag on GCC, but I want the errors to trigger properly for the rest of my code.
Is there a way I can enable it just for this one header file (perhaps similar to #pragma GCC diagnostic XXX).
There's #pragma GCC optimize "blah" or the function attribute __attribute__((optimize("blah"))) that act like the argument -fblah was given for the rest of that file/that specific function, but it doesn't seem to work with -fpermissive:
$ cat foo.cpp
#pragma GCC optimize "permissive"
void foo(int x) {
}
$ g++-8 -c -Wall -Wextra foo.cpp
foo.cpp:1:22: warning: bad option ‘-fpermissive’ to pragma ‘optimize’ [-Wpragmas]
#pragma GCC optimize "permissive"
^~~~~~~~~~~~
foo.cpp:3:16: warning: bad option ‘-fpermissive’ to attribute ‘optimize’ [-Wattributes]
void foo(int x) {
One option would be to put the function that needs this in a file by itself, and configure your build system to compile just that file with -fpermissive, though that breaks the header-only model. Or fix the code so it doesn't need that option at all.
Per gcc man page:
-fpermissive
Downgrade some diagnostics about nonconformant code from errors to warnings. Thus, using -fpermissive allows some nonconforming code to compile.
So in theory, one can allow a section to compile as permissive using a sequence of gcc warning pragmas:
// Start permissive code
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-result"
#pragma GCC diagnostic ignored "-Wuninitialized"
// .. Other #pragmas
// Permissive Code here.
// Restore normal processing.
#pragma GCC diagnostic pop
One challenge is that there is no published list of errors that will be ignored with -fpermissive (At least I could not find it). One possible approach will be to compile the code, and enter the '#pragma's one at at a time, until the code compiles cleanly.
If one can identify all (or most) of the rules, possible to put them into #include file.
#pragma GCC diagostic push
#include "permissive.h"
// Permissive Code here
#pragma GCC diagostic pop
I'm compiling on with GCC on Linux, but CMake is kind enough to produce a Clang compatible compilation database. This means that I can run fancy, modern Clang based tools on my codebase and those tools have perfect knowledge of how each file is to be built (flags, defines, include paths, etc.) So far so good.
But today the Clang based static analysis in my IDE started showing a Clang specific warning. I don't think it particularly matters for my question which warning it is, but it was warning: disabled expansion of recursive macro, generated by -Wdisabled-macro-expansion. This particular macro is provided by a third party, so fixing the warning isn't an option, but I would like to suppress it as it occurs several times in the file in question.
What I'm struggling with is how to suppress the warning in Clang based analysis tools without causing new warnings in the GCC build.
Adding #pragma clang diagnostic ignored "-Wdisabled-macro-expansion" suppresses the warning for Clang tools, but causes GCC to issue warning: ignoring #pragma clang diagnostic [-Wunknown-pragmas].
Similarly, adding #pragma GCC diagnostic ignored "-Wdisabled-macro-expansion" suppresses the Clang warning (because Clang tries to be compatible with GCC diagnostics), but causes GCC to issue warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas].
Wrapping either of the above with #ifdef __clang__ makes GCC happy, but doesn't suppress the Clang warning because the tooling is smart enough to know that the code isn't compiled with __clang__, but with __GNUC__ instead.
Is there a way to make a diagnostic #pragma visible to Clang tooling, but not to GCC?
the tooling is smart enough to know that the code isn't compiled with __clang__, but with __GNUC__ instead
If it's reporting a clang-only warning, but does not think that __clang__ is defined, that sounds like a problem with the tooling. If it's trying to be that clever about misrepresenting itself, you may be up a creek... but also you should be complaining to the tool author for creating this situation in the first place.
That said, you could try:
#if defined(__has_warning)
# if __has_warning("-Wdisabled-macro-expansion")
# pragma GCC diagnostic ignored "-Wdisabled-macro-expansion"
# endif
#endif
I'm not sure if this will work... it depends on how hard the tooling is pretending to not be clang (__has_warning is a clang-only extension).
I am including a file from a third-party library that raises an error that can be downgraded to a warning with -fpermissive. But because I do not want to "pollute" my compilation log with these warnings, I want to completely disable this messages.
So far, I set the -fpermissive option with a diagnostic pragma when including the file; something like:
#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-fpermissive"
#include <third-party-file.h>
#pragma GCC diagnostic pop
Since GCC usually provides both a "positive" and "negative" version of the -f flags, I thought about ignoring the "no-permissive" feature:
#pragma GCC diagnostic ignored "-fno-permissive"
#include <third-party-file.h>
But there does not seem to be a "negative" version of the -fpermissive flag (I am using GCC 4.6.3; but even the version 4.7.0 does not have it).
Can I mimic this behavior?
tldr: You cannot turn off the fpermissive output after GCC 4.7.
Just posting this here so it has more visibility: unfortunately, zwol's answer (while well-intentioned, and potentially helpful to those with older GCC versions) does not work for more recent versions of GCC. From GCC 4.8 and beyond, you cannot turn off the fpermissive output. o11c in his comment to the OP helpfully provides the following bug which tracks this:
Bug 81787. [5/6/7/8 Regression] #pragma GCC diagnostic warning "-fpermissive" no longer
Note that it is in the state "RESOLVED INVALID", so the inability to turn it off is the expected behavior and there are no plans to change it.
One of these ought to do what you wanted:
#pragma GCC diagnostic ignored "-fpermissive"
or
#pragma GCC diagnostic ignored "-pedantic"
"ignored" is how you squelch a diagnostic entirely, and the inverse of -fpermissive is -pedantic, for historical reasons.
While developing a C++ application, I had to use a third-party library which produced a huge amount of warnings related with a harmless #pragma directive being used.
../File.hpp:1: warning: ignoring #pragma ident
In file included from ../File2.hpp:47,
from ../File3.hpp:57,
from File4.h:49,
Is it possible to disable this kind of warnings, when using the GNU C++ compiler?
I believe you can compile with
-Wno-unknown-pragmas
to suppress these.
In GCC, compile with -Wno-unknown-pragmas
In MS Visual Studio 2005 (this question isn't tagged with gcc, so I'm adding this for reference), you can disable globally in Project Settings->C/C++->Advanced. Enter 4068 in "Disable Specific Warnings"
or you can add this to any file to disable warnings locally
#pragma warning (disable : 4068 ) /* disable unknown pragma warnings */
Perhaps see GCC Diagnostic Pragmas? Alternatively in this case you could use the combination of options that -Wall enables, excluding -Wunknown-pragmas.
I know the question is about GCC, but for people wanting to do this as portably as possible:
Most compilers which can emit this warning have a way to disable the warning from either the command line (exception: PGI) or in code (exception: DMC):
GCC: -Wno-unknown-pragmas / #pragma GCC diagnostic ignored "-Wunknown-pragmas"
Clang: -Wno-unknown-pragmas / #pragma clang diagnostic ignored "-Wunknown-pragmas"
Intel C/C++ Compiler: -diag-disable 161 / #pragma warning(disable:161)
PGI: #pragma diag_suppress 1675
MSVC: -wd4068 / #pragma warning(disable:4068)
TI: --diag_suppress,-pds=163 / #pragma diag_suppress 163
IAR C/C++ Compiler: --diag_suppress Pe161 / #pragma diag_suppress=Pe161
Digital Mars C/C++ Compiler: -w17
Cray: -h nomessage=1234
You can combine most of this into a single macro to use in your code, which is what I did for the HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS macro in Hedley
#if HEDLEY_HAS_WARNING("-Wunknown-pragmas")
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("clang diagnostic ignored \"-Wunknown-pragmas\"")
#elif HEDLEY_INTEL_VERSION_CHECK(16,0,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("warning(disable:161)")
#elif HEDLEY_PGI_VERSION_CHECK(17,10,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress 1675")
#elif HEDLEY_GNUC_VERSION_CHECK(4,3,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("GCC diagnostic ignored \"-Wunknown-pragmas\"")
#elif HEDLEY_MSVC_VERSION_CHECK(15,0,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS __pragma(warning(disable:4068))
#elif HEDLEY_TI_VERSION_CHECK(8,0,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress 163")
#elif HEDLEY_IAR_VERSION_CHECK(8,0,0)
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS _Pragma("diag_suppress=Pe161")
#else
# define HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
#endif
Note that Hedley may have more complete information than this answer since I'll probably forget to update this answer, so if you don't want to just use Hedley (it's a single public domain C/C++ header you can easily drop into you project) you might want to use Hedley as a guide instead of the information above.
The version checks are probably overly pessimistic, but sometimes it's hard to get good info about obsolete versions of proprietary compilers, and I'd rather be safe than sorry. Again, Hedley's information may be better.
Many compilers can also push/pop warnings onto a stack, so you can push, then disable them before including code you don't control, then pop so your code will still trigger the warning in question (so you can clean it up). There are macros for that in Hedley, too: HEDLEY_DIAGNOSTIC_PUSH / HEDLEY_DIAGNOSTIC_POP.
In my case, I work with Qt under MinGW. I need to set the flag another way, in my .PRO file:
QMAKE_CXXFLAGS_WARN_ON += -Wno-unknown-pragmas