don't assert when a module re-exports a module and one of its symbols (…

…swiftlang#64479)

rdar://106807038

lib/AST/Module.cpp

@@ -1397,6 +1397,9 @@ void ModuleDecl::getDisplayDecls(SmallVectorImpl<Decl*> &Results, bool Recursive
     llvm::SmallDenseMap<ModuleDecl *, SmallPtrSet<Decl *, 4>, 4> QualifiedImports;
     collectParsedExportedImports(this, Modules, QualifiedImports);
     for (const auto &QI : QualifiedImports) {
+      auto Module = QI.getFirst();
+      if (Modules.contains(Module)) continue;
+
       auto &Decls = QI.getSecond();
       Results.append(Decls.begin(), Decls.end());
     }

test/SymbolGraph/Module/DuplicateExportedImport.swift

@@ -0,0 +1,11 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend %S/Inputs/DuplicateExportedImport/A.swift -module-name A -emit-module -emit-module-path %t/A.swiftmodule
+// RUN: %target-swift-frontend %s -module-name DuplicateExportedImport -emit-module -emit-module-path /dev/null -I %t -emit-symbol-graph -emit-symbol-graph-dir %t/
+// RUN: %FileCheck %s --input-file %t/DuplicateExportedImport.symbols.json
+
+// REQUIRES: asserts
+
+// CHECK-COUNT-1: "precise":"s:1A8ClassTwoC"
+
+@_exported import A
+@_exported import class A.ClassTwo

test/SymbolGraph/Module/Inputs/DuplicateExportedImport/A.swift

@@ -0,0 +1,3 @@
+public class ClassOne {}
+
+public class ClassTwo {}