[Issue 17630] DMD treats imports as public imports when selectively imported

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17630

--- Comment #2 from Seb <greensunny12 at gmail.com> ---
> Can you investigate this a bit more and add that info to the bug report, including that it's been around for a while?


The leaked symbols are [found in the local `symtab`
table](https://github.com/dlang/dmd/blob/master/src/ddmd/dsymbol.d#L1306)

```
test17630b.ScopeDsymbol::search(ident='Erase', flags=x0)
    found in locals = 'test17630b.Erase'
test17630b.ScopeDsymbol::search(ident='Erase', flags=x28)
    found in locals = 'test17630b.Erase'
```

However, the next four lines in the log shouldn't happen:

```
test17630a.ScopeDsymbol::search(ident='Erase', flags=x0)
    found in locals = 'test17630a.Erase'
test17630a.ScopeDsymbol::search(ident='Erase', flags=x28)
    found in locals = 'test17630a.Erase'
__anonymous.ScopeDsymbol::search(ident='Erase', flags=x8)
    found in locals = '__anonymous.Erase'
```

Now, when I look at the symbol table for test17630b it's built correctly:

```
DsymbolTable::insert(this = 0x7fc6d7dcbbe0, 'object')
DsymbolTable::insert(this = 0x7fc6d7dcbbe0, 'Erase')
DsymbolTable::insert(this = 0x7fc6d7dcbbe0, 'NoErase')
```

In fact even the members only get added for test17630b:

```
Import.addMember(this=object, sd=test17630b, sc=0x7f11f8e71b00)
Dsymbol::addMember('object')
Dsymbol::addMember(this = 0x7f11f8e71c20, 'object' scopesym = 'test17630b')
Dsymbol::addMember(this = 0x7f11f8e71c20, 'object' sds = 0x7f11fa2c2db0,
sds.symtab = 0x7f11f8e71d30)
Dsymbol::addMember('Erase')
Dsymbol::addMember(this = 0x7f11fa2c3aa0, 'Erase' scopesym = 'test17630b')
Dsymbol::addMember(this = 0x7f11fa2c3aa0, 'Erase' sds = 0x7f11fa2c2db0,
sds.symtab = 0x7f11f8e71d30)
Dsymbol::addMember('NoErase')
Dsymbol::addMember(this = 0x7f11fa2c3c60, 'NoErase' scopesym = 'test17630b')
Dsymbol::addMember(this = 0x7f11fa2c3c60, 'NoErase' sds = 0x7f11fa2c2db0,
sds.symtab = 0x7f11f8e71d30)
```

and in the main test file `Erase` doesn't get inserted into the symbol table:

```
__anonymous.ScopeDsymbol::search(ident='_Dmain', flags=x8)
__entrypoint.ScopeDsymbol::search(ident='_Dmain', flags=x28)
    found in locals = '__entrypoint._Dmain'
Import::semantic('imports.test17630a.object') object
test17630a.ScopeDsymbol::importScope(object, 2)
Import::semantic('imports.test17630a.imports') test17630b
test17630a.ScopeDsymbol::importScope(test17630b, 2)
Import::semantic('imports.test17630b.object') object
test17630b.ScopeDsymbol::importScope(object, 2)
DsymbolTable::insert(this = 0x7f975b424780, 'fail17630')
DsymbolTable::insert(this = 0x7f975b424850, 'imports')
DsymbolTable::insert(this = 0x7f975b424920, 'imports')
DsymbolTable::insert(this = 0x7f975b4249f0, 'fail17630')
Import::semantic('__anonymous') test17630a
Import::load('__anonymous') 0x7f975c8294b0
```


> This seems like a fairly important import leak remaining, would be good to explore how large it is. 

It's _pretty_ large. AFAICT all module-level imports, non-selective imports
leak their symbols.
However, even selective imports leak their selected symbols:

```d
import imports.test17630b; // works __falsely__ as public import
import imports.test17630b : Erase; // works __falsely__ as public import
```

Funnily even `private import X;` doesn't fix it.

--