Merge pull request #32193 from bitjammer/acgarland/rdar-63058801-dont-emit-empty-sgf

[SymbolGraph] Don't emit extension symbol graphs if empty

Author: bitjammer

lib/SymbolGraphGen/SymbolGraph.h

@@ -226,6 +226,11 @@ struct SymbolGraph {
   /// Returns `true` if the declaration is a requirement of a protocol
   /// or is a default implementation of a protocol
   bool isRequirementOrDefaultImplementation(const ValueDecl *VD) const;
+
+  /// Returns `true` if there are no nodes or edges in this graph.
+  bool empty() const {
+    return Nodes.empty() && Edges.empty();
+  }
 };
 
 } // end namespace symbolgraphgen

lib/SymbolGraphGen/SymbolGraphGen.cpp

@@ -74,6 +74,9 @@ symbolgraphgen::emitSymbolGraphForModule(ModuleDecl *M,
   Success |= serializeSymbolGraph(Walker.MainGraph, Options);
 
   for (const auto &Entry : Walker.ExtendedModuleGraphs) {
+    if (Entry.getValue()->empty()) {
+      continue;
+    }
     Success |= serializeSymbolGraph(*Entry.getValue(), Options);
   }
 

test/SymbolGraph/EmptyExtension.swift

@@ -0,0 +1,8 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift %s -module-name EmptyExtension -emit-module -emit-module-path %t/
+// RUN: %target-swift-symbolgraph-extract -module-name EmptyExtension -I %t -pretty-print -output-dir %t
+// RUN: %{python} -c 'import os.path; import sys; sys.exit(1 if os.path.exists(sys.argv[1]) else 0)' %t/[email protected]
+
+extension Sequence {
+  func foo() {}
+}