[Lldb-commits] [lldb] Reapply [lldb][DWARF] Delay struct/class/union definition DIE searching when parsing declaration DIEs. (PR #98361)

[Zequan Wu via lldb-commits]

================
@@ -1631,26 +1638,48 @@ bool SymbolFileDWARF::CompleteType(CompilerType &compiler_type) {
     return true;
   }
 
-  DWARFDIE dwarf_die = GetDIE(die_it->getSecond());
-  if (dwarf_die) {
-    // Once we start resolving this type, remove it from the forward
-    // declaration map in case anyone child members or other types require this
-    // type to get resolved. The type will get resolved when all of the calls
-    // to SymbolFileDWARF::ResolveClangOpaqueTypeDefinition are done.
-    GetForwardDeclCompilerTypeToDIE().erase(die_it);
+  DWARFDIE decl_die = GetDIE(die_it->getSecond());
+  // Once we start resolving this type, remove it from the forward
+  // declaration map in case anyone's child members or other types require this
+  // type to get resolved.
+  GetForwardDeclCompilerTypeToDIE().erase(die_it);
+  DWARFDIE def_die = FindDefinitionDIE(decl_die);
+  if (!def_die) {
+    SymbolFileDWARFDebugMap *debug_map_symfile = GetDebugMapSymfile();
+    if (debug_map_symfile) {
+      // We weren't able to find a full declaration in this DWARF, see
+      // if we have a declaration anywhere else...
+      def_die = debug_map_symfile->FindDefinitionDIE(decl_die);
+    }
+  }
+  if (!def_die) {
+    // No definition found. Proceed with the declaration die. We can use it to
+    // create a forward-declared type.
+    def_die = decl_die;
+  }
 
-    Type *type = GetDIEToType().lookup(dwarf_die.GetDIE());
+  Type *type = ResolveType(def_die);
----------------
ZequanWu wrote:

`ResolveType(def_die)` just do [this part](https://github.com/llvm/llvm-project/pull/98361/files/37b6878b9125c314c75053f7d5b0ba520111e9a3#diff-5dd6736e4d6c38623630df16c4494c1a8b099716ee0f05c9af54b4bafb1d864eR1607-R1674) of work and then return the type, which was created from the declaration DIE. It doesn't create a loop or recursion. We need it to do the work when finding existing type in the UniqueDWARFASTTypeMap, which is basically this block: https://github.com/llvm/llvm-project/pull/98361/files/37b6878b9125c314c75053f7d5b0ba520111e9a3#diff-5dd6736e4d6c38623630df16c4494c1a8b099716ee0f05c9af54b4bafb1d864eR1648-R1674. Those code are important to keep some maps(`GetDIEToType()`, `LinkDeclContextToDIE`, `UniqueDWARFASTTypeMap`) updated.

https://github.com/llvm/llvm-project/pull/98361