Jon Ross-Perkins

Fix accidental name exposure on cross-package import use.

1

Looking at `export` handling, I noticed and figured to fix this case first. Also makes the test file prelude-agnostic.

Rename Directive->Decl in general, BindExport->BindDecl

2

Mechanically, replacing Directive->Decl, directive->declaration, _declaration->_decl (to avoid comments). Context: https://discord.com/channels/655572317891461132/963846118964350976/1241145948625703062

Switch the prelude to using 'export import'.

1

Note, I assume this doesn't affect all the TODOs (like for i32.carbon), but does cut some things down (and requires updating some tests that have prelude name conflicts, but I...

Unify handling of transitive imports between current and other packages.

1

This makes cross-package `export import` work. Note collisions still occur with cross-package "export name".

Switch type literals to use builtin functions.

2

Modifies the core package and literal handling to use factory functions for standard type literals. Updates function/builtin/import.carbon to stop depending on the prelude, since it would list all the impls...

Fix handling for indirectly imported entities.

1

A member of an imported entity can be an ImportRefUnloaded in an imported SemIR. To address this, find a loaded version of it for use.

Each entity is restricted to one, optional `extern` declaration. If used, it must be imported by the defining library. The defining library annotates the existence of an `extern` with the...

Alternative naming for `has_extern` keyword

4

### Summary of issue: #3980 is looking for a keyword to mark that an entity has an `extern` declaration. Tentatively it uses `has_extern`; is there a different name that leads...

Note I'm mostly trying to capture [the docs](https://docs.google.com/document/d/1RRYMm42osyqhI2LyjrjockYCutQ5dOf8Abu50kTrkX0/edit?resourcekey=0-kHyqOESbOHmzZphUbtLrTw&tab=t.0) as they exist today, not fixing issues with the docs. Trying to organize it a little better though, particularly so that it...