Rollup merge of #38418 - michaelwoerister:def_path_cleanup, r=eddyb

Cleanup refactoring around DefPath handling

This PR makes two big changes:
* All DefPaths of a crate are now stored in metadata in their own table (as opposed to `DefKey`s as part of metadata `Entry`s.
* The compiler will no longer allocate a pseudo-local DefId for inlined HIR nodes (because those are gross). Inlined HIR nodes will have a NodeId but they don't have there own DefId anymore. Turns out they were not needed anymore either. Hopefully HIR inlining will be gone completely one day but if until then we start needing to be able to map inlined NodeIds to original DefIds, we can add an additional table to metadata that allows for reconstructing this.

Overall this makes for some nice simplifications and removal of special cases.

r? @eddyb

cc @rust-lang/compiler

src/librustdoc/clean/mod.rs

@@ -2801,7 +2801,7 @@ impl Clean<Item> for doctree::Macro {
             visibility: Some(Public),
             stability: self.stab.clean(cx),
             deprecation: self.depr.clean(cx),
-            def_id: cx.tcx.map.local_def_id(self.id),
+            def_id: self.def_id,
             inner: MacroItem(Macro {
                 source: format!("macro_rules! {} {{\n{}}}",
                                 name,

src/librustdoc/doctree.rs

@@ -233,9 +233,11 @@ pub struct DefaultImpl {
     pub whence: Span,
 }
 
+// For Macro we store the DefId instead of the NodeId, since we also create
+// these imported macro_rules (which only have a DUMMY_NODE_ID).
 pub struct Macro {
     pub name: Name,
-    pub id: ast::NodeId,
+    pub def_id: hir::def_id::DefId,
     pub attrs: hir::HirVec<ast::Attribute>,
     pub whence: Span,
     pub matchers: hir::HirVec<Span>,

src/librustdoc/visit_ast.rs

@@ -85,7 +85,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                                               None);
         // attach the crate's exported macros to the top-level module:
         let macro_exports: Vec<_> =
-            krate.exported_macros.iter().map(|def| self.visit_macro(def)).collect();
+            krate.exported_macros.iter().map(|def| self.visit_local_macro(def)).collect();
         self.module.macros.extend(macro_exports);
         self.module.is_crate = true;
     }
@@ -211,7 +211,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     // FIXME(jseyfried) merge with `self.visit_macro()`
                     let matchers = def.body.chunks(4).map(|arm| arm[0].get_span()).collect();
                     om.macros.push(Macro {
-                        id: def.id,
+                        def_id: def_id,
                         attrs: def.attrs.clone().into(),
                         name: def.ident.name,
                         whence: def.span,
@@ -514,12 +514,12 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
     }
 
     // convert each exported_macro into a doc item
-    fn visit_macro(&self, def: &hir::MacroDef) -> Macro {
+    fn visit_local_macro(&self, def: &hir::MacroDef) -> Macro {
         // Extract the spans of all matchers. They represent the "interface" of the macro.
         let matchers = def.body.chunks(4).map(|arm| arm[0].get_span()).collect();
 
         Macro {
-            id: def.id,
+            def_id: self.cx.tcx.map.local_def_id(def.id),
             attrs: def.attrs.clone(),
             name: def.name,
             whence: def.span,