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digitalmars.D.learn - File, line and message for assert(0)?

reply simendsjo <simen.endsjo pandavre.com> writes:
void f() {
     // much code with many assert(0)
     assert(0, "where's my message, line and file?");
     // much code with many assert(0)
}

void main() {
     f();
}


object.Error: assert(0) or HLT instruction
----------------
assert_release.d(8): _Dmain
----------------

Is it possible to get file, line and message for assert(0)?
May 28 2011
parent reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
Works for me, 2.053 XP32:

core.exception.AssertError testsassert.d(3): where's my message, line and file?
May 28 2011
parent reply simendsjo <simen.endsjo pandavre.com> writes:
On 28.05.2011 17:56, Andrej Mitrovic wrote:

 Works for me, 2.053 XP32:

 core.exception.AssertError testsassert.d(3): where's my message, line and file?


Compiling with -release?
May 28 2011
parent reply "Vladimir Panteleev" <vladimir thecybershadow.net> writes:
On Sat, 28 May 2011 19:19:25 +0300, simendsjo <simen.endsjo pandavre.com>  
wrote:


 On 28.05.2011 17:56, Andrej Mitrovic wrote:

 Works for me, 2.053 XP32:

 core.exception.AssertError testsassert.d(3): where's my message, line  
 and file?


 Compiling with -release?


http://www.d-programming-language.org/expression.html#AssertExpression  
says:

The expression assert(0) is a special case; it signifies that it is  
unreachable code. Either AssertError is thrown at runtime if it is  
reachable, or the execution is halted (on the x86 processor, a HLT  
instruction can be used to halt execution). The optimization and code  
generation phases of compilation may assume that it is unreachable code.

-- 
Best regards,
  Vladimir                            mailto:vladimir thecybershadow.net
May 28 2011
next sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
FTFY:

import std.exception;
void f() {
   // much code with many assert(0)
   enforce(0, "where's my message, line and file?");
   // much code with many assert(0)
}

void main() {
   f();
}

But the two are supposed to be used for different things.
May 28 2011
prev sibling parent reply simendsjo <simen.endsjo pandavre.com> writes:
On 28.05.2011 18:22, Vladimir Panteleev wrote:

 On Sat, 28 May 2011 19:19:25 +0300, simendsjo
 <simen.endsjo pandavre.com> wrote:


 On 28.05.2011 17:56, Andrej Mitrovic wrote:

 Works for me, 2.053 XP32:

 core.exception.AssertError testsassert.d(3): where's my message, line
 and file?


 Compiling with -release?


 http://www.d-programming-language.org/expression.html#AssertExpression
 says:

 The expression assert(0) is a special case; it signifies that it is
 unreachable code. Either AssertError is thrown at runtime if it is
 reachable, or the execution is halted (on the x86 processor, a HLT
 instruction can be used to halt execution). The optimization and code
 generation phases of compilation may assume that it is unreachable code.


I don't think I understand the use case for assert(0) then.. I thought 
it was just a way getting assert in release mode.
May 28 2011
parent reply Michel Fortin <michel.fortin michelf.com> writes:
On 2011-05-28 12:32:59 -0400, simendsjo <simen.endsjo pandavre.com> said:


 I don't think I understand the use case for assert(0) then.. I thought 
 it was just a way getting assert in release mode.


The use case for assert(0) is the same as any assert(whatever): 
checking for things that shouldn't happen. Normally compiling in 
release mode would strip all the asserts to make things slimmer and 
faster. But given there is no cost in checking for assert(0), those are 
not stripped, they are just replaced with a halt instruction. So the 
assert's still there, but you don't have a message for it nor the line 
number.

If you want to see where the assertion happens, you can either compile 
in non-release mode or you can hook a debugger to your release 
executable and wait for the assert to happen.

-- 
Michel Fortin
michel.fortin michelf.com
http://michelf.com/
May 28 2011
parent simendsjo <simen.endsjo pandavre.com> writes:
On 28.05.2011 19:56, Michel Fortin wrote:

 On 2011-05-28 12:32:59 -0400, simendsjo <simen.endsjo pandavre.com> said:


 I don't think I understand the use case for assert(0) then.. I thought
 it was just a way getting assert in release mode.


 The use case for assert(0) is the same as any assert(whatever): checking
 for things that shouldn't happen. Normally compiling in release mode
 would strip all the asserts to make things slimmer and faster. But given
 there is no cost in checking for assert(0), those are not stripped, they
 are just replaced with a halt instruction. So the assert's still there,
 but you don't have a message for it nor the line number.

 If you want to see where the assertion happens, you can either compile
 in non-release mode or you can hook a debugger to your release
 executable and wait for the assert to happen.


Thanks to both.

I got confused about by Vladimir's comment: "The optimization and code 
generation phases of compilation may assume that it is unreachable code."

I tested this now, and the compiler does indeed complain about 
unreachable code.

And the debugger also breaks, so it makes more sense now :)
May 28 2011