QOpenGLShaderProgram: is possible to make error output nice? - qt

I'm implementing some numerical algorithms on GPU via OpenGL and Qt.
But i am not very familiar with it.
I want to extract some functions from my current shader to some "shader library" and use it in my other shaders by string interpolation. It not hard to implement but i don't know how handle shader's compile errors
I use following code to compile shader
QOpenGLShaderProgram *shaderProgram = new QOpenGLShaderProgram();
if (!shaderProgram->addShaderFromSourceFile(QOpenGLShader::Fragment,fragmentShaderFileName)) {
qDebug() << "Failed to compile fragment shader";
//..........
When some compile error appears Qt print following message (an example)
QOpenGLShader::compile(Fragment): 0:331(9): error: syntax error, unexpected NEW_IDENTIFIER, expecting ',' or ';'
*** Problematic Fragment shader source code ***
//my shader source code
Is possible to catch error line number and use it to build my own error message? (with highlighted line)

According to the Qt documentation, you can use QOpenGLShaderProgram::log():
Returns the errors and warnings that occurred during the last link()
or addShader() with explicitly specified source code.
You can then parse the resulting string to build your own error message.

Related

Frama-C aborted Invalid user input

I am very new to Frama-c and I got an issue when I am trying to open a C source file.
The error shows as
"fatal error: event.h: No such file or directory. Compilation terminated".
[kernel] Parsing FRAMAC_SHARE/libc/__fc_builtin_for_normalization.i (no preprocessing)
[kernel] Parsing WorkSpace/bipbuffer.c (with preprocessing)
[kernel] user error: failed to run: gcc -E -C -I. -dD -D__FRAMAC__ -nostdinc -D__FC_MACHDEP_X86_32 -I/usr/share/frama-c/libc -o '/tmp/bipbuffer.ce6d077.i' '/home/xxx/WorkSpace/bipbuffer.c' you may set the CPP environment variable to select the proper preprocessor command or use the option "-cpp-command".
[kernel] user error: stopping on file "/home/xxx/WorkSpace/bipbuffer.c" that has errors. Add'-kernel-msg-key pp' for preprocessing command.
So bascially I am trying to open a C source file but it returns an error like this. I aslo tried other very simple C files like hello world and other slicing functions, it works well.
I thought it was because I didn't have the dependencies of 'event.h' but it still return these errors after I installed the libevent dependencies. I am not sure if I need to manually set some path of the dependencies for frama-c
Here is part of the C file (Source link: https://memcached.org/) that I would like to open:
#include "stdio.h"
#include <stdlib.h>
/* for memcpy */
#include <string.h>
#include "bipbuffer.h"
static size_t bipbuf_sizeof(const unsigned int size)
{
return sizeof(bipbuf_t) + size;
}
int bipbuf_unused(const bipbuf_t* me)
{
if (1 == me->b_inuse)
/* distance between region B and region A */
return me->a_start - me->b_end;
else
return me->size - me->a_end;
}
......
Thanks,
Compilers and other tools working with C source code need to know where to find header files. There are some standard places where they look automatically, but Frama-C has fewer of those than (and different ones from) a normal compiler.
You need to find out where event.h is installed, then pass something like -cpp-extra-args "-I /path/to/directory/" to Frama-C. Pass the directory name only, not including the name event.h itself.
In addition to Isabelle Newbie's answer, I'd like to point out that the Chlorine version of Frama-C, whose beta has been recently announced, features a new option -json-compilation-database that attempts to read the arguments to be passed to the pre-processor from a compilation database.
Such database can be generated directly by cmake, but there are solutions for make-based project such as the one you refer to, in particular bear, which intercepts the commands launched by make to build the database.
Here's a detailed summary of how you could proceed, using the new -json-compilation-database option from Frama-C 17 Chlorine, plus an extra script list_files.py (which is not in the beta, but will be available in the final 17 release, and can be downloaded here):
Get the source files you want to analyze with Frama-C, run ./configure, and if possible try to disable optional dependencies from external libraries; for instance, some code bases include optional dependencies based on availability of libraries/system features, but have fallback options (resorting to standard C library or POSIX functions). The more you give Frama-C, the better the chances of analyzing it well, so if such external libraries are not essential, excluding them might help get a more "POSIXy" code, which should help. This is typically visible in config.h files, in macros commonly named HAVE_*.
Compile and install Build EAR or some equivalent tool to obtain a compile_commands.json file.
Run bear make (or cmake with flag CMAKE_EXPORT_COMPILE_COMMANDS) to get the compile_commands.json file.
Run the aforementioned list_files.py in the directory containing compile_commands.json to obtain the list of C sources used during compilation.
Run Frama-C (17 Chlorine or newer), giving it the list of sources found in the previous step, plus option -json-compilation-database . to parse the compile_commands.json and, hopefully, get the appropriate preprocessing flags.
Ideally, this should suffice, but in practice, this is rarely enough. In particular due to the presence of external libraries and non-C99, non-POSIX functions, the following steps are always needed.
6. Inclusion of external libraries
At this step, Frama-C will complain about the lack of event.h. You'll have to include the headers of this library yourself. Note: copying headers directly from your /usr/include is not likely to work, due to several architecture-specific definitions, especially files such as bits/*.h..
Instead, consider downloading the external libraries and preparing them (e.g. running ./configure at least). Then manually add the extra include directory via -cpp-extra-args="-I <path/to/your/sources/for/libevent.h>/include".
7. Inclusion of missing non-POSIX headers
Some other headers may be missing, in particular GNU- or BSD-specific sources (e.g. sysexits.h). Get these headers and add them when necessary. The error message in this case comes from the preprocessor (gcc) and is similar to this:
memcached.c:51:10: fatal error: sysexits.h: No such file or directory
#include <sysexits.h>
^~~~~~~~~~~~
compilation terminated.
8. Definition of missing non-POSIX types and constants
At this point, all necessary headers should be available, but parsing with Frama-C may still fail. This is due to usage of non-POSIX type definitions (e.g. caddr_t, struct ling), non-POSIX constants (e.g. MAXPATHLEN, SOCK_NONBLOCK, NI_MAXSERV). Error messages typically resemble the following:
[kernel] memcached.c:3261: Failure: Cannot resolve variable MAXPATHLEN
Constants are often easy to provide manually, by grepping what's available in your /usr/include.
Type definitions, on the other hand, may require some copy-pasting at the right places, especially if they depend on other types which are also missing. This step is hardly automatizable, but relatively straightforward once you get used to some specific error messages.
For instance, the following error message is related to a missing type definition (caddr_t):
[kernel] Parsing memcached.c (with preprocessing)
[kernel] memcached.c:1074:
syntax error:
Location: line 1074, between columns 38 and 47, before or at token: c
1072 *hdr++ = 0;
1073 *hdr++ = 0;
1074 assert((void *) hdr == (caddr_t)c->msglist[i].msg_iov[0].iov_base + UDP_HEADER_SIZE);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1075 }
1076
Note that the token just before c is (caddr_t), which has never been defined (it is often defined as either void * or char *).
The following error message is related to an incomplete type, i.e., a struct used somewhere but never defined:
[kernel] memcached.c:5811: User Error:
variable `ling' has initializer but incomplete type
It means that variable ling's type, which is struct linger (non-POSIX), has never been defined. In this case, we can copy it from our /usr/include/bits/socket.h:
struct linger
{
int l_onoff; /* Nonzero to linger on close. */
int l_linger; /* Time to linger. */
};
Note: if there are POSIX constants/definitions missing from Frama-C's libc, consider notifying its developers, or proposing pull requests in Frama-C's Github.
9. Fixing incompatible and missing function prototypes
Parsing is likely to succeed after the previous step, but it may still fail due to incompatible function prototypes. For instance, you may get:
[kernel] User Error: Incompatible declaration for usleep:
different integer types int and unsigned int
First declaration was at assoc.c:238
Current declaration is at items.c:1573
This is the consequence of a warning emitted earlier:
[kernel:typing:implicit-function-declaration] slabs.c:1150: Warning:
Calling undeclared function usleep. Old style K&R code?
It means that function usleep is called, but it does not have a prototype, therefore Frama-C uses the pre-C99 convention of "implicit int": it generates such a prototype, but later in the code, an actual declaration of usleep is found, and its type is not int. Hence the error.
To prevent this, you need to ensure usleep's prototype is properly included. Since it is not POSIX.1-2008, you need to either define/undefine the appropriate macros (see unistd.h), or add your own prototype.
At the end, this should allow Frama-C to parse the files and build an AST.
However, there are several missing prototypes yet; we were just lucky that none conflicted with actual declarations. Ideally, you'll consider the parsing stage done when there are no more messages such as implicit-function-declaration and similar warnings.
Some of the missing prototypes in memcached, such as getsubopt, are POSIX and should be integrated into Frama-C's standard library. Others might make part of a small library of non-standard stubs, to be reused for other software.
Contributing with results for future reuse
Successful conclusion of the parsing stage for such open source libraries is enough to consider them for integration into this repository of open source case studies, so that future users can start their analyses without having to redo all of these steps. (The repository is oriented towards Eva, but not exclusively: parsing is useful for all of Frama-C plug-ins.)

Strange and unknown error while compiling QT code

I don't know why I am getting error or these statements. The same code works fine when I compile it for x86_64 system but when I changed target to Beaglebone Black and switched to angstrom tool chain the QTcreator started giving error in these lines.
//connect(process, &QProcess::readyReadStandardError, [=]{
ui->textBrowser->append(process->readAllStandardError());
});
connect(process, &QProcess::readyReadStandardOutput, [=]{
ui->textBrowser->append(process->readAllStandardOutput());
});
Errors are for the expression "[=]". Infact I don't know why this error is coming. Could this be related to version, bcoz BBB is have qt4-embedded. Any help would be appreciated.
The syntax for connecting signal to c++11 lambda has been added to Qt 5. Since previous version (Qt4) doesn't define the right signature for connect(), you can't use it. You should transform your code to match the correct syntax:
connect(process, SIGNAL(readyReadStandardError()), receiver, SLOT(yourCustomSlot()) );
With a slot declared as follow:
class MyReceiverClass {
slots:
void yourCustomSlot() {
ui->textBrowser->append(process->readAllStandardOutput());
}
};

Coding errors between the Arduino Uno and SDI-12 interface on Decagon Devices

I have been working on a project recently using a sensor for electrical conductivity in soil (A 5TE sensor from Decagon Devices) with my Arduino Uno. I am ready to code, and found this example code on GitHub (the example code is there when you scroll down the page). When trying to run it on the latest version of Arduino, it gave me these compilation errors:
sketch_dec15a:7: error: expected initializer before 'void'
sketch_dec15a:4: error: 'SDISerial' does not name a type
sketch_dec15a:9: error: expected initializer before 'void'
sketch_dec15a.ino: In function 'void loop()':
sketch_dec15a:22: error: 'connection' was not declared in this scope
NOTE: I believe I installed the library correctly, but am not 100% certain...more like 85%.
What's wrong with the code and how can it be made to work?
The example code is wrong. Look at the compilation errors. The first thing it says is:
sketch_dec15a:7: error: expected initializer before 'void'
So what it's saying is that it found something that said void and expected to see something else first. void occurs only twice in your code, so we can't be far. Let's take a look at the code immediately surrounding it the first void:
char tmp_buffer[4];
char sensor_info[]
//initialize variables
void setup(){
connection.begin();
Serial.begin(9600);//so we can print to standard uart
//small delay to let the sensor do its startup stuff
delay(3000);//3 seconds should be more than enough
}
Right before the void setup(){ is //initialize variables. That's just a comment, and not code, so it doesn't relly count. Looking back one more line we see:
char sensor_info[]
Something is wrong with that line. Work on it and see if you can figure it out (check the other lines for "hints"). If you can't figure it out, the answer is right below (put your mouse over it to see it):
It needs a semicolon ";" at the end to complete the statement. Because the semicolon is missing, it thinks "void setup(){" is part of the previous statement.

problems compiling and running Nachos

First issue: I am trying to import stdlib.h in order to use functions like malloc() and rand(). I am working in threadtest.cc , folder threads. This is the error I get after
#include <stdlib.h>
In file included from ../threads/threadtest.cc:18:0:
/usr/include/stdlib.h:146:33: error: declaration of ‘double atof(const char*) throw ()’ has a different exception specifier
In file included from ../threads/utility.h:57:0,
from ../threads/system.h:12,
from ../threads/threadtest.cc:13:
../machine/sysdep.h:62:8: error: from previous declaration ‘double atof(const char*)’
In file included from ../threads/threadtest.cc:18:0:
/usr/include/stdlib.h:149:33: error: declaration of ‘int atoi(const char*) throw ()’ has a different exception specifier
In file included from ../threads/utility.h:57:0,
from ../threads/system.h:12,
from ../threads/threadtest.cc:13:
../machine/sysdep.h:61:5: error: from previous declaration ‘int atoi(const char*)’
In file included from ../threads/threadtest.cc:18:0:
/usr/include/stdlib.h:771:60: error: declaration of ‘int abs(int) throw ()’ has a different exception specifier
In file included from ../threads/utility.h:57:0,
from ../threads/system.h:12,
from ../threads/threadtest.cc:13:
../machine/sysdep.h:63:5: error: from previous declaration ‘int abs(int)’
../threads/threadtest.cc: In function ‘void shout(int)’:
../threads/threadtest.cc:83:25: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
What can be a reason for this?
Second issue: I am trying to give a forked new thread a name.
Thread * t = new Thread ("my id");
t->Fork(shout, S);
And testing it in function shout:
printf ("%s", currentThread->getName());
This example works fine.
However, if I want to give the thread a "dynamic" id, I use:
sprintf(id, "%d", i);
Thread * t = new Thread (id);
With the same printf for currentThread->getName() it gets me junk:
x�ӿ����_ ���
I have used example from the Nachos documentation as well as tried different ways to transmit a dynamic id using string functions, but nothing worked, only junk.
Thank you for any answers.
I had the same problem in my Nachos homework.
My roommate said maybe it's a incompatibility problem, and suggested that I delete "stdlib.h".
It worked!

mingw spitting countless warnings about ignoring "dll import" attribute

I'm using mingw32-make to compile a qt project that uses opengl, it compiles correctly and everything, but it spits countless warning messages of the form:
c:/qt3/include/qcolor.h:67: warning: inline function `int qGray(int, int,
int)' declared as dllimport: attribute ignored
For this particular instance, the function declaration is:
Q_EXPORT inline int qGray( int r, int g, int b )// convert R,G,B to gray 0..255
{ return (r*11+g*16+b*5)/32; }
My question is, why is it spitting all these warning? how can I silence them without silencing other legitimate warnings (i.e. warnings that are related directly to my code and could be potential problems)?
More importantly, why is mingw ignoring the dll import attribute in the first place?
I think Qt ought to only define Q_EXPORT (Q_DECL_EXPORT in Qt 4) to be the dllexport/import attribute if one of the following macros is defined, so make sure your makefiles or code that includes Qt headers (which eventually will include qglobal.h) aren't defining any of them: WIN32, _WIN32, __WIN32__, WIN64, _WIN64, __WIN64__. Or you can just define Q_EXPORT to be nothing in your compile (or preprocessor) flags, then Qt should skip defining it.

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