extern(C++) const ref to static array incorrectly adds const to the mangle name

[dlangBugzillaToGithub]

Nicholas Wilson (@thewilsonator) reported this on 2019-06-11T14:04:23Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=19953

CC List

• kinke

Description

short test27(int (& const arr)[6][291]) { return 0;};

with MSVC gives warning C4227: anachronism used: qualifiers on reference are ignored

and hence mangles as 

?test27@@YAFAE_A_Y15BCD@H@Z (without the underscores, A being mutable)

whereas DMD mangles

extern(C++) short test27(const ref int[291][6] t);

 as 

?test27@@YAFAE_B_Y15BCD@H@Z (without the underscores, B being const).

[dlangBugzillaToGithub]

kinke commented on 2019-06-11T16:51:18Z

The `const` in the D signature doesn't apply to the reference itself, but to the type, i.e., is the same as `ref const(int[291][6])`, and as such your C++ example isn't an analogon.

Proper analogon with a 1D array, showing that the problem goes somewhat deeper:

C++:          short test27(const int (&)[291]);
Win64 mangle: ?test27@@YAFAEAY0BCD@$$CBH@Z

D:            extern(C++) short test27(const ref int[291])
Win64 mangle: ?test27@@YAFAEBY0BCD@H@Z

[dlangBugzillaToGithub]

kinke commented on 2019-06-11T19:18:43Z

Related issue for Linux x64:

C++: short test27(const int (&)[6][291])
     _Z6test27RA6_A291_Ki

D:   extern(C++) short test27(ref const int[291][6])
     _Z6test27RKA6_KA291_Ki

Note that the C++ mangling of `const(int[291][6])` and `const(int)[291][6]` is identical for both MSVC and Itanium (and that's fine IMO).