Templated TypeInfo

[andralex]

Starting small. This duplicates the implementation in https://github.com/dlang/druntime/blob/master/src/rt/typeinfo/ti_int.d. The idea is, of course, that the templated implementation will replace implementations for all scalar types. For testing purposes I restricted it to int.

The thing works if typeid(int) lowers to RTTypeid!(int). The use of eponymous templates elegantly hides the type name.

[dlang-bot]

Thanks for your pull request, @andralex!

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Testing this PR locally

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dub run digger -- build "master + druntime#3174"

[andralex]

I took upon painting the bikeshed by changing the name from RTTypeid to __typeid. Reasons:

• A value with a capitalized name breaks the convention used everywhere in druntime and phobos
• The whole thing is awkward to type - was that RTTypeID or RTTypeId or...?
• The moment someone sees __typeid they'll figure a connection with typeid. With RTTypeid, they'll have to run to the manual.

[wilzbach]

__typeid

__ is reserved for compiler internals like auto-generated variables. For runtime template hooks we typically use _d_.

[n8sh]

__typeid

__ is reserved for compiler internals like auto-generated variables. For runtime template hooks we typically use _d_.

Wouldn't this be okay for the same reason as __cmp, __move_post_blt, __switch_error, etc?

[andralex]

Added statically-typed versions of all functions, so if people write typeid(T).func in generic code, an efficient version is picked up.

[UplinkCoder]

Mind the 32bit platforms. hash_t is 32bit there.

[andralex]

Per discussions with @WalterBright, it turns out it's not reasonably feasible to do an incremental replacement. The plan instead is to develop __typeid separately from the built-in typeid, and replace uses of the latter with the former. At the very end we adjust typeid to lower to __typeid.

Currently no support for struct, class, and interface.

[andralex]

Blocked by:

• https://issues.dlang.org/show_bug.cgi?id=21141
• https://issues.dlang.org/show_bug.cgi?id=21142
• https://issues.dlang.org/show_bug.cgi?id=21143
• https://issues.dlang.org/show_bug.cgi?id=21144
• https://issues.dlang.org/show_bug.cgi?id=21145
• https://issues.dlang.org/show_bug.cgi?id=21146