[GiNaC-devel] Fix the compliation error *for real*

[Alexei Sheplyakov]

Dear Jens,

On Fri, Jul 31, 2009 at 12:50:26PM +0200, Jens Vollinga wrote:

> commit eaf81b3115697a8e883848ace0ceb919cf443b2c
> Author: Jens Vollinga <jensv at balin.nikhef.nl>
> Date:   Fri Jul 31 11:14:01 2009 +0200
> 
>     Fixed cast that caused compile error on 64bit machines.

Unfortunately the error is still here:

libtool: compile:  ccache g++-4.1 -DHAVE_CONFIG_H -I. -I../../../../work/sw/GiNaC/ginac -I../config -I/home/pc7135/varg/target/x86_64-linux-gnu/include -Wall -O2 -g -pipe -funroll-loops -ffast-math -finline-limit=1200 -m64 -march=k8 -mfpmath=sse -msse2 -MT parser.lo -MD -MP -MF .deps/parser.Tpo -c ../../../../work/sw/GiNaC/ginac/parser/parser.cpp  -fPIC -DPIC -o .libs/parser.o
../../../../work/sw/GiNaC/ginac/parser/parser.cpp: In member function `GiNaC::ex GiNaC::parser::parse_identifier_expr()':
../../../../work/sw/GiNaC/ginac/parser/parser.cpp:73: error: cast from `GiNaC::ex (*)(const GiNaC::exvector&)' to `unsigned int' loses precision


A simple test case:
$ cat > test.cc << EOF 
unsigned test(const void* ptr)
{
	return reinterpret_cast<unsigned>(ptr);
}
EOF
$ g++ test.cc
test.cc: In function `unsigned int test(const void*)':
test.cc:3: error: cast from `const void*' to `unsigned int' loses precision


I think the compiler is right since [expr.reinterpret.cast] says:
"A pointer can be explicitly converted to any integral type large enough
to hold it."


The patch below fixes the problem.

From: Alexei Sheplyakov <varg at metalica.kh.ua>
Subject: [PATCH] Fix compilation error on 64-bit architectures for real.

According to [expr.reinterpret.cast] it's not ok to convert a pointer
into an integer of a different size.

---
 ginac/parser/parser.cpp |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/ginac/parser/parser.cpp b/ginac/parser/parser.cpp
index 6ed364f..cfa313b 100644
--- a/ginac/parser/parser.cpp
+++ b/ginac/parser/parser.cpp
@@ -70,7 +70,8 @@ ex parser::parse_identifier_expr()
 	// pointers.
 	GiNaC::function* f = NULL;
 	try {
-		f = new GiNaC::function(reinterpret_cast<unsigned>(reader->second), args);
+		unsigned serial = (unsigned)(unsigned long)(void *)(reader->second);
+		f = new GiNaC::function(serial, args);
 	}
 	catch ( std::runtime_error ) {
 		if ( f ) delete f;
-- 
1.6.3.3

Best regards,
	Alexei