[Issue 18955] extern(C++) default struct mangling is overridden when interacting with a `cppmangle = class` tamplate

Jun 08, 2018

Jul 12, 2018

https://issues.dlang.org/show_bug.cgi?id=18955 Manu <turkeyman@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |C++, industry --- Comment #1 from Manu <turkeyman@gmail.com> --- This symptom is a result of the same logic that causes the related ICE at typesem.d:~1310 I don't understand the logic, perhaps Walter can take a look who understands the intent of that code? --

https://issues.dlang.org/show_bug.cgi?id=18955 Mike Franklin <slavo5150@yahoo.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |slavo5150@yahoo.com --- Comment #2 from Mike Franklin <slavo5150@yahoo.com> --- `alias string = basic_string!(char, char_traits!char);` has two template arguments, but `extern (C++, class) struct basic_string(T, Traits, Alloc)` had 3. This results in: Error: template instance `basic_string!(char, char_traits!char)` does not match template declaration I'm not sure what I should be doing to reproduce the problem. --

July 12, 2018

[Issue 18955] extern(C++) default struct mangling is overridden when interacting with a `cppmangle = class` tamplate

Posted by Manu

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Manu

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https://issues.dlang.org/show_bug.cgi?id=18955

--- Comment #3 from Manu <turkeyman@gmail.com> ---
I'm sorry. I think I must have cut&paste fail-ed. Remove the `Alloc` arg:
-------------------------------
extern (C++, std)
{
        struct char_traits(Char)
        {
        }
        extern (C++, class) struct basic_string(T, Traits)
        {
        }
        alias test_string = basic_string!(char, char_traits!char);
}
extern (C++) void test(ref const(std.test_string) str) {}
pragma(msg, test.mangleof);
-------------------------------

Compile that, it will emit:
  ?test@@YAXAEBV?$basic_string@DV?$char_traits@D@std@@@std@@@Z
But it should emit:
  ?test@@YAXAEBV?$basic_string@DU?$char_traits@D@std@@@std@@@Z

Notice the 'V?$char_traits' (class) should be a 'U?$char_traits' (struct);
char_traits is a struct.

If you add:
    extern (C++, struct) struct char_traits(Char)

ie, tell it explicitly to mangle the struct as a struct, it mangles correctly. Of course, a struct should mangle as a struct naturally though.

--

https://issues.dlang.org/show_bug.cgi?id=18955 --- Comment #8 from github-bugzilla@puremagic.com --- Commits pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/768198c87f562de08c3dfb8b1d32ace9287d1617 Fix Issue 18955 - extern(C++) default struct mangling is overridden when interacting with a cppmangle = class template https://github.com/dlang/dmd/commit/51c1138fae497b11f05890413ec9e323d2948bee Merge pull request #8631 from JinShil/fix_18955 Fix Issue 18955 - extern(C++) default struct mangling is overridden when interacting with a cppmangle = class template --

https://issues.dlang.org/show_bug.cgi?id=18955 --- Comment #9 from github-bugzilla@puremagic.com --- Commits pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/a1a87203a1f01c79a96ffbc1a45cece2fed6501e add test for issue 18955 https://github.com/dlang/dmd/commit/00f4c42c92da7fd590a8edf8dc6c6562fe988fe4 Merge pull request #8708 from rainers/test_18955 add test for issue 18955 merged-on-behalf-of: Petar Kirov <ZombineDev@users.noreply.github.com> --

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