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Report From: Delphi-BCB/Compiler/C++/Front End/Language [ Add a report in this area ]

Report #: 54835

Status: Closed

sometimes when C-array is used in templates its size can be set only with literal

Project: C++Builder

Build #: 10.0.2166.28377

Version: 10.0

Submitted By: Sergiy Kanilo

Report Type: Crash / Data loss / Total failure

Date Reported: 11/14/2007 10:45:42 AM

Severity: Commonly encountered problem

Last Updated: 3/20/2012 2:24:39 AM

Platform: All versions

Internal Tracking #: 256430

Resolution: Fixed (Resolution Comments)

Resolved in Build: : 12.0.3140.16150

Duplicate of: None

Voting and Rating

Overall Rating: (1 Total Rating)

5.00 out of 5

Total Votes: 15

Description

one of the simple ways to get information in compile time is to return a reference to array of different size and take its sizeof,
for example

template<typename T>
char (&f(T const&))[1];

unfortunately in BDS2006 that could cause internal compiler error if the size of array is anyhing but literal

enum
{

Q =2
};
int const P =2;

template<typename T> char ( &f( T& ) )[ 2 ]; //1
//template<typename T> char ( &f( T& ) )[ 1+1 ]; //2
//template<typename T> char ( &f( T& ) )[ Q ]; //3
//template<typename T> char ( &f( T& ) )[ P ]; //4

int main(int argc, char* argv[])
{

int v;

int p =sizeof( f( v ) );
}

compiles and runs fine, when array size is literal

comment line //1 and uncomment line //2 - array size is expression
compilations gives
[C++ Fatal Error] Unit1.cpp(15): F1004 Internal compiler error at ...

the same errors when size is enum and constant (line //3 and //4)

Steps to Reproduce:

Expression:
bcc32 -c qc54835a.cpp

Exp: Clean compile
Act:
Fatal F1004 qc54835c.cpp 15: Internal compiler error at 0x43e8ad with base 0x400000 in function main(int,char *)
Fatal F1004 qc54835c.cpp 15: Internal compiler error in function main(int,char*)

with enum:
bcc32 -c qc54835b.cpp
same results

with const:
bcc32 -c qc54835c.cpp
same results

Workarounds

wrap array in structure

template<int N>
struct AN
{
char array[N];
};

template<typename T> AN<1+1> f( T& );

int main(int argc, char* argv[])
{

int v;

int p =sizeof( f( v ).array );
}

Attachment

qc54835.zip

Comments

None

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QualityCentral Delphi-BCB Compiler C++ Front End access Bitfields Destructors Diagnostics Exception Handling Extensions Initialization Inline Assembly Invocation Language Mangling Scheme Namespaces Object Generation Overloading Pragmas Pre-Compiled Headers Preprocessor Refactoring RTTI Templates

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