Webkit: Conversion from string literal loses const qualifier

[Ali Ebrahimi]

Hi,

On Thu, Apr 14, 2016 at 11:30 AM, Murali Billa <murali.billa at oracle.com>
wrote:

> Hi Ali,
>
> Are you getting error due to 2nd OR 3rd parameter?    As per your error,
> you are getting error for 3rd parameter right? As you already know, we
> fixed the issue for 3rd parameter.
>
> ..\..\..\..\src\main\native\Source\WebCore\platform\java\api\BackFo
> >>>> rwardListJava.cpp(46)
> >>>> : error C2664: 'jmethodID initMethod(JNIEnv *,jclass,char *,const
> >>>> char *)' : cannot convert argument 3 from 'const char [7]' to 'char *'
> >>>>          Conversion from string literal loses const qualifier (see
> >>>> /Zc:strictStrings)
>
> I tried to reproduce the error for 2nd parameter with VS 2013 professional
> + update 5 on windows 7 64 bit. But Im not able to get the error for 2nd
> parameter and code is building successfully.
>

I build with VS2013 utimate update 5 on win 8.1 64 bit with WinSDK 8.1 and
get compile error. So I can not say anything here.


> Can you please confirm about which parameter(2nd/3rd) is causing the error
> for you?
>

I think indexing start from 1 in error msgs. argument 1, argument 2, ...
The error relates to parameter *name *in initMethod.

Please follow error msgs more precisely:

..\..\..\..\src\main\native\Source\WebCore\platform\java\api\BackForwardListJava
.cpp(46) : error C2664: 'jmethodID initMethod(JNIEnv *,jclass,char *,const
char*)' : cannot convert argument 3 from 'const char [7]' to 'char *'
        Conversion from string literal loses const qualifier (see
/Zc:strictStrings)
Line 46:

*    return initMethod(env, cls, "<init>", signature);*

Here, argument 3 is *"<init>"* (*const char [7]*) and its target type is *"char
*"* in initMethod signature. So here code implicitly tries to convert const
string to non-const string. If you want compiler not complain here you
should explicitly cast string literal to "char *".
    return initMethod(env, cls, *(char*)*"<init>", signature);


..\..\..\..\src\main\native\Source\WebCore\platform\java\api\BackForwardListJava
.cpp(87) : error C2664: 'jmethodID initMethod(JNIEnv *,jclass,char *,const
char*)' : cannot convert argument 3 from *'const char [18]'* to 'char *'
        Conversion from string literal loses const qualifier (see
/Zc:strictStrings)

Line 87:

    static jmethodID notifyItemChangedMID = initMethod(env,
getJEntryClass(), "notifyItemChanged", "()V");

Here, argument 3 is *"notifyItemChanged" *with type  *'const char [18]' *and
its target type is *"char *"* in initMethod signature.
Above error reason and workaround applies here.

    static jmethodID notifyItemChangedMID = initMethod(env,
getJEntryClass(), (*char**)"notifyItemChanged", "()V");

..\..\..\..\src\main\native\Source\WebCore\platform\java\api\BackForwardListJava
.cpp(98) : error C2664: 'jmethodID initMethod(JNIEnv *,jclass,char *,const
char*)' : cannot convert argument 3 from *'const char [20]' *to 'char *'
        Conversion from string literal loses const qualifier (see
/Zc:strictStrings)
Line 98:

            initMethod(env, getJEntryClass(), "notifyItemDestroyed", "()V");

Here, argument 3 is "notifyItemDestroyed" with compiler type *'const char
[20]' *and target type is *"char *"* in initMethod signature.

Again all same.
workaound:

            initMethod(env, getJEntryClass(), (*char**)"notifyItemDestroyed",
"()V");

..\..\..\..\src\main\native\Source\WebCore\platform\java\api\BackForwardListJava
.cpp(311) : error C2664: 'jmethodID initMethod(JNIEnv *,jclass,char *,const
char *)' : cannot convert argument 3 from 'const char [14]' to 'char *'
        Conversion from string literal loses const qualifier (see
/Zc:strictStrings)

Line 311:

    static jmethodID notifyChangedMID = initMethod(
        env,
    getJBFLClass(),
        "notifyChanged",
        "()V");

Finally, here argument 3 is "notifyChanged" with compiler type *'const char
[14]' *and target type is *"char *"* in initMethod signature.

So, same error and workaound:
    static jmethodID notifyChangedMID = initMethod(
        env,
    getJBFLClass(),
        (*char**)"notifyChanged",
        "()V");

So we have two way,
1: add all above casts
2: change initMethod signature:
static jmethodID initMethod(JNIEnv* env, jclass cls, *const *char* name,
const char* signature)


Both works for me, but I vote for option 2.

What do you think?

-- 

Best Regards,
Ali Ebrahimi