https://issues.dlang.org/show_bug.cgi?id=13294

Denis Shelomovskij <verylonglogin.reg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
            Summary|[IFTI] IFTI fails for       |[IFTI] IFTI fails or works
                   |function with const and     |incorrectly for function
                   |mutable `ref` parameters of |with const and mutable
                   |`[u]byte`/`[u]short`        |`ref` parameters of most
                   |                            |types

--- Comment #1 from Denis Shelomovskij <verylonglogin.reg@gmail.com> ---
It's not just these four integral types. For most other types `const` is incorrectly added. This code should compile fine:
---
void f(T)(const ref T src, ref T dest) // T is const char here
{
    static assert(!is(T == const)); // fails
}

void main()
{
    const char src;
    char dest;
    f(src, dest);
}
---

Note: static assert passes for `int`/`uint`/`long`/`ulong` and floating point types.

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https://issues.dlang.org/show_bug.cgi?id=13294

Denis Shelomovskij <verylonglogin.reg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |CTFE

--- Comment #2 from Denis Shelomovskij <verylonglogin.reg@gmail.com> ---
(In reply to Denis Shelomovskij from comment #1)
> For most other types `const` is incorrectly added.

And because of CTFE bug 13295 all modifications of such variables disappear, thus in worst case causing nasty wrong-code bugs.

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https://issues.dlang.org/show_bug.cgi?id=13294

--- Comment #3 from Denis Shelomovskij <verylonglogin.reg@gmail.com> ---
(In reply to Denis Shelomovskij from comment #2)
> (In reply to Denis Shelomovskij from comment #1)
> > For most other types `const` is incorrectly added.
> 
> And because of CTFE issue 13295 all modifications of such variables disappear, thus in worst case causing nasty wrong-code bugs.

But as some modifications disappear anyway (because of issue 13297) and thus one can't reliably use `ref` in CTFE it's probably isn't that big problem.

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https://issues.dlang.org/show_bug.cgi?id=13294

--- Comment #4 from Vladimir Panteleev <thecybershadow@gmail.com> ---
Introduced in https://github.com/D-Programming-Language/dmd/pull/3801

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https://issues.dlang.org/show_bug.cgi?id=13294

Marc Schütz <schuetzm@gmx.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |schuetzm@gmx.net

--- Comment #5 from Marc Schütz <schuetzm@gmx.net> ---
User Xinok report a problem on the forums, which is probably related to this
bug:
http://forum.dlang.org/post/bnwtzwmqnrhpvwvxnzkn@forum.dlang.org

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https://issues.dlang.org/show_bug.cgi?id=13294

Paul D. Anderson <paul.d.anderson@comcast.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |safety0ff.bugz@gmail.com

--- Comment #6 from Paul D. Anderson <paul.d.anderson@comcast.net> ---
*** Issue 13351 has been marked as a duplicate of this issue. ***

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https://issues.dlang.org/show_bug.cgi?id=13294

--- Comment #7 from Denis Shelomovskij <verylonglogin.reg@gmail.com> ---
(In reply to Paul D. Anderson from comment #6)
> *** Issue 13351 has been marked as a duplicate of this issue. ***

So here is testcase for those issue:
---
void f1(T)(in T) { T t; ++t; }
void f2(T)(in T, in T) { T t; ++t; } // (line 2)

void main()
{
    const double n;
    f1(n);     // ok
    f2(n, n);  // error (line 8)
}
---
main.d(2): Error: cannot modify const expression nan
main.d(8): Error: template instance main.f2!(const(double)) error instantiating
---

Compiler carries in case there is more than one argument.

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https://issues.dlang.org/show_bug.cgi?id=13294

--- Comment #8 from Denis Shelomovskij <verylonglogin.reg@gmail.com> ---
(In reply to Denis Shelomovskij from comment #7)
> ...carries in case...

*carries `const` in case

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https://issues.dlang.org/show_bug.cgi?id=13294

Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|CTFE                        |pull

--- Comment #9 from Kenji Hara <k.hara.pg@gmail.com> ---
https://github.com/D-Programming-Language/dmd/pull/3896

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https://issues.dlang.org/show_bug.cgi?id=13294

github-bugzilla@puremagic.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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