[Issue 14901] [reg 2.067/2.068] template static shared this() run multiple times with separate compilation

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14901

--- Comment #1 from Kenji Hara <k.hara.pg at gmail.com> ---
The bug behavior has introduced by the excessive instantiation and codegen for
the non-root instances. From 2.067, the make!"bar" instance code which aliased
in b.d will be instantiated and stored into [bcde].obj. With 2.066 and earlier,
it had stored only into b.obj.

Those regressions have the same root:

Issue 14431 - [REG 2.067.0] huge slowdown of compilation speed
Issue 14508 - [REG2.067.0] compiling with -unittest instantiates templates in
non-root modules
Issue 14564 - [REG2.067] dmd -property -unittest combination causes compiler
error

and it will be fixed by:

https://github.com/D-Programming-Language/dmd/pull/4784

But unfortunately, my PR is not released into 2.068.0, because Walter couldn't
understand the fix.
David, I wish to you to join its code review, if you have a time.

----

> As far as the cause for this goes, for reasons I'm not entirely clear about a unique identifier is used for function name of the static ctor (e.g. _sharedStaticCtor55). For (amongst others) -unittest builds, the ctor function is always emitted to fix issue 11239. Thus, different object files end up with differently named copies of the same function, which consequently also gets run multiple times.

That's an another, fragile naming mechanism issue in current dmd front-end.
Some unnamed symbols (static this, unittest, anonymous class, etc) are numbered
by the `Identifier::generateId()`. It's result not *stable* because it fully
depends on the order of semantic analysis and it will be changed by the
conditional compilation.

For lambdas and unnamed mixin declarations, I added "scope local unique number"
(See FuncExp::genIdent and TemplateMixin::semantic).
For them, the frequency of the issue has been reduced by them, but it's not yet
perfect answer...

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