Do not convert from string literal to wchar_t*

Do not convert from string literal to wchar_t*

R=brucedawson@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/9478b521b01a9cc94a0d6cfe43b8e0341b5b82eb

[Bo Xu, 2015-01-08 22:45:42]

bo_xu@foxitsoftware.com changed reviewers:
+ brucedawson@chromium.org

[Bo Xu, 2015-01-08 22:45:43]

Hi Bruce, buiding in linxu, clang complains that "can not convert from string
literal to wchar_t*".

[brucedawson, 2015-01-08 22:52:08]

Better solution. Look for opportunities to mark variables with const -- it
prevents this, and bugs, and can make intentions clearer.

https://codereview.chromium.org/841203002/diff/1/xfa/src/fxfa/src/fm2js/xfa_f...
File xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp (right):

https://codereview.chromium.org/841203002/diff/1/xfa/src/fxfa/src/fm2js/xfa_f...
xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp:3961: FX_WCHAR strCode[] =
L"0123456789abcdef";
That is not the ideal fix. The compiler is pointing out that the string literal
has type "const wchar_t*" and converting that to "wchar_t*" is deprecated.

By far the better fix is to put 'const' in front of FX_WCHAR. I am of the belief
that most variables should be const because most variables don't actually vary.
This particular declaration should be "const FX_WCHAR* const strCode" because we
don't want the pointer or the characters to change.

Switching to an array means that the characters will actually be copied, which
is probably more expensive and is not desirable unless you want to modify the
characters.

So, "const FX_WCHAR* const".

[Bo Xu, 2015-01-08 22:55:39]

https://codereview.chromium.org/841203002/diff/1/xfa/src/fxfa/src/fm2js/xfa_f...
File xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp (right):

https://codereview.chromium.org/841203002/diff/1/xfa/src/fxfa/src/fm2js/xfa_f...
xfa/src/fxfa/src/fm2js/xfa_fm2jscontext.cpp:3961: FX_WCHAR strCode[] =
L"0123456789abcdef";
On 2015/01/08 22:52:08, brucedawson wrote:
> That is not the ideal fix. The compiler is pointing out that the string
literal
> has type "const wchar_t*" and converting that to "wchar_t*" is deprecated.
> 
> By far the better fix is to put 'const' in front of FX_WCHAR. I am of the
belief
> that most variables should be const because most variables don't actually
vary.
> This particular declaration should be "const FX_WCHAR* const strCode" because
we
> don't want the pointer or the characters to change.
> 
> Switching to an array means that the characters will actually be copied, which
> is probably more expensive and is not desirable unless you want to modify the
> characters.
> 
> So, "const FX_WCHAR* const".

You are right! Now use FX_LPCWSTR as elsewhere.

[Bo Xu, 2015-01-08 23:04:54]

> So, "const FX_WCHAR* const".

Is patch 2 ok? Or I can change to const FX_WCHAR* const as you pointed out.

[brucedawson, 2015-01-09 00:13:05]

lgtm

[brucedawson, 2015-01-09 00:14:04]

On 2015/01/09 00:13:05, brucedawson wrote:
> lgtm

const FX_LPCWSTR is perfect.

[Bo Xu, 2015-01-09 00:29:35]

Committed patchset #3 (id:40001) manually as
9478b521b01a9cc94a0d6cfe43b8e0341b5b82eb (presubmit successful).