[modules] Remove redundant import of lexical decls when building a lookup table

for a DeclContext, and fix propagation of exception specifications along
redeclaration chains.

This reverts r232905, r232907, and r232907, which reverted r232793, r232853,
and r232853.

One additional change is present here to resolve issues with LLDB: distinguish
between whether lexical decls missing from the lookup table are local or are
provided by the external AST source, and still look in the external source if
that's where they came from.

llvm-svn: 232928

1 files changed, 34 insertions, 6 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index e15e532be19..0b406184058 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -3021,17 +3021,45 @@ static void LookupVisibleDecls(DeclContext *Ctx, LookupResult &Result,
   if (Visited.visitedContext(Ctx->getPrimaryContext()))
     return;
 
+  // Outside C++, lookup results for the TU live on identifiers.
+  if (isa<TranslationUnitDecl>(Ctx) &&
+      !Result.getSema().getLangOpts().CPlusPlus) {
+    auto &S = Result.getSema();
+    auto &Idents = S.Context.Idents;
+
+    // Ensure all external identifiers are in the identifier table.
+    if (IdentifierInfoLookup *External = Idents.getExternalIdentifierLookup()) {
+      std::unique_ptr<IdentifierIterator> Iter(External->getIdentifiers());
+      for (StringRef Name = Iter->Next(); !Name.empty(); Name = Iter->Next())
+        Idents.get(Name);
+    }
+
+    // Walk all lookup results in the TU for each identifier.
+    for (const auto &Ident : Idents) {
+      for (auto I = S.IdResolver.begin(Ident.getValue()),
+                E = S.IdResolver.end();
+           I != E; ++I) {
+        if (S.IdResolver.isDeclInScope(*I, Ctx)) {
+          if (NamedDecl *ND = Result.getAcceptableDecl(*I)) {
+            Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
+            Visited.add(ND);
+          }
+        }
+      }
+    }
+
+    return;
+  }
+
   if (CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(Ctx))
     Result.getSema().ForceDeclarationOfImplicitMembers(Class);
 
   // Enumerate all of the results in this context.
   for (const auto &R : Ctx->lookups()) {
-    for (auto *I : R) {
-      if (NamedDecl *ND = dyn_cast<NamedDecl>(I)) {
-        if ((ND = Result.getAcceptableDecl(ND))) {
-          Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
-          Visited.add(ND);
-        }
+    for (auto *D : R) {
+      if (auto *ND = Result.getAcceptableDecl(D)) {
+        Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
+        Visited.add(ND);
       }
     }
   }