bug#24271: 25.1; font-lock problem of c++-mode

[Eli Zaretskii <eliz@gnu.org>]

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Forwarding to the bug tracker, since the response was sent only to me:

> From: Jiajian Huang <wherejoystarts@gmail.com>
> Date: Sat, 20 Aug 2016 15:39:58 +0800
> 
> Hi, Thanks for your reply.
> 
> I’m not meaning to write invalid C++ program intentionally, like making a “int test” into “in test”.
> 
> When we’re typing “int test”, we type the “i” first then “n”, then “t”, then “ “(space), then “test”, namely,
> 
> “i” -> “in” -> “int” -> “int “ -> … -> “int test”,
> 
> even “normally” typing, the syntax keeping changing. Let’s keep tracking this procedure.
> 
> 
> 
> As you can see, none of the above images shows a “valid” C++ program. But the color(or the font style) has at least
> changed twice. Base on what you’ve point out, the color should change once the “i” is input  and keep unbold till image 4 
> since none of them is valid.
> 
> This could happen in any other place when typing in c++-mode, like
> 
> Example 1
> 
> 
> Why the “vector” in the first image and third is not turn into “bold red” ?
> Why the “vec” in the second image is turn into “bold red” ?
> 
> Example 2
> 
> 
> This is a more serious example. As you can see, I normally input such a short line “using std::string”, the color have change 6 times !
> I don’s think any of them is a “valid” C++ program except the last one.
> 
> I’ve not seen any other major mode has such a “feature”. This is my first time get into c++-mode. Because of this mechanism,
> the current input area keep “flashing” too much when keep typing fast within a buffer full of words even under such a light color theme. 
> I feel that it’s so different from other major mode(python-mode etc.) soon as I switch to c++-mode. Maybe it’s not a bug, but I don’t think it’s a good feature.
> 
> Thanks.

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