Merge pull request swiftlang#74708 from artemcm/ConstExtractWMOMacroExpansionExtraction

[Compile Time Constant Extraction] Ensure macro-expanded declarations are visited in WMO

Author: artemcm

lib/ConstExtract/ConstExtract.cpp

@@ -572,6 +572,13 @@ gatherConstValuesForModule(const std::unordered_set<std::string> &Protocols,
   NominalTypeConformanceCollector ConformanceCollector(Protocols,
                                                        ConformanceDecls);
   Module->walk(ConformanceCollector);
+  // Visit macro expanded extensions
+  for (auto *FU : Module->getFiles())
+    if (auto *synthesizedSF = FU->getSynthesizedFile())
+      for (auto D : synthesizedSF->getTopLevelDecls())
+        if (isa<ExtensionDecl>(D))
+          D->walk(ConformanceCollector);
+
   for (auto *CD : ConformanceDecls)
     Result.emplace_back(evaluateOrDefault(CD->getASTContext().evaluator,
                                           ConstantValueInfoRequest{CD, Module},

test/ConstExtraction/ExtractFromMacroExpansion.swift

@@ -7,6 +7,10 @@
 // RUN: %target-swift-frontend -typecheck -emit-const-values-path %t/ExtractFromMacroExpansion.swiftconstvalues -const-gather-protocols-file %t/protocols.json -primary-file %s -load-plugin-library %t/%target-library-name(MacroDefinition)
 // RUN: cat %t/ExtractFromMacroExpansion.swiftconstvalues 2>&1 | %FileCheck %s
 
+// Do the same, but ensure the WMO compilation flow produces the same result
+// RUN: %target-swift-frontend -typecheck -emit-const-values-path %t/ExtractFromMacroExpansionWMO.swiftconstvalues -const-gather-protocols-file %t/protocols.json -O %s -load-plugin-library %t/%target-library-name(MacroDefinition)
+// RUN: cat %t/ExtractFromMacroExpansionWMO.swiftconstvalues 2>&1 | %FileCheck %s
+
 protocol MyProto { }
 
 @freestanding(declaration, names: named(MacroAddedStruct))