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Date: Fri, 30 Sep 2011 11:16:55 +0200
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To: =?ISO-8859-1?Q?=C1ngel_Gonz=E1lez?= <keisial@gmail.com>
Cc: Andrey Hristov <php@hristov.com>, Gustavo Lopes <glopes@nebm.ist.utl.pt>, internals@lists.php.net
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Subject: Re: [PHP-DEV] Cast trap with INI entries compiling C++ extension
From: olivier@yakaz.com (Olivier Favre)

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I keep on having the following error:
    ERROR:
    =E2=8B=85 Incorrect Captcha
while trying to file a bug on the following page:
    https://bugs.php.net/report.php
(Debian sid, Google Chrome 14.0.835.186)

I tried flushing my cookies.
There are two opened bug reports about that:
 - https://bugs.php.net/bug.php?id=3D54380
 - https://bugs.php.net/bug.php?id=3D53255
And I would have liked to file another... if only I could!


Anyway, if someone else is luckier, here what I'd have liked to file:

PHP version: 5.3.8
Package affected: Compile issues/Compilation warning
Bug type: Feature/Change request
OS: All (seen under Linux)
Summary: char* field should be const char* to avoid C++ warning
Description:
http://news.php.net/php.internals/55662

I'm writing a C++ extension to PHP.
When declaring a INI entry I get the following warning, multiple times:
warning: deprecated conversion from string constant to 'char*' [-Wwrite-str=
ings]

This only arises when compiling with a C++ compiler.
The right and easy fix seems to set some fields to const char *.
Some may even be set to const char * const (but this alternative seems
to be used
nowhere).

The proposed patch is against the php5-dev-5.3.8-2 package of debian sid:
PHP 5.3.8-2 with Suhosin-Patch (cli) (built: Sep 12 2011 07:28:26)
- - -
Test script:
Write a C++ extension:
config.m4 should contain PHP_REQUIRE_CXX().

Declare your module:
zend_module_entry quezako_module_entry =3D {
    STANDARD_MODULE_HEADER,
    "YourExtensionName", // (1 warning here)
    [...],
    "0.42", // (1 warning here)
    [...],
    STANDARD_MODULE_PROPERTIES_EX
};

Declare an INI entry:
PHP_INI_BEGIN()
STD_PHP_INI_ENTRY(
    "extensionName.variable", // (1 warning here)
    "default value", // (1 warning here)
    [...]
)
PHP_INI_END()
- - -
Patch name: field_constness_cpp_compilation_warning_fix.patch
Patch file: (see attached file)
Expected result:
No compilation warning.
- - -
Actual result:
Multiple of the following warning:
warning: deprecated conversion from string constant to 'char*' [-Wwrite-str=
ings]

Using the very common fix of prepending (char*) to the string constant is
especially harmful here, because of ZEND_INI_ENTRY3_EX using sizeof() on in=
: it
returns 4/8 (32/64bits platform).
Using a cast to char[] solves the problem, but the above fix is a very very
common mistake.

If the target fields were const char*, no compilation warning would be rose=
.
- - -
Solve the problem 17 + 23 =3D ?: 40 (I even checked the answer using a
calculator!!!!)
Submit: Send bug report (I'm going mad, really...)

--
Olivier Favre
Software engineer
Yakaz
www.yakaz.com

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