[ASTImporter] Set redecl chain of functions before any other import

Summary:
FunctionDecl import starts with a lookup and then we create a new Decl.
Then in case of CXXConstructorDecl we further import other Decls
(base classes, members through CXXConstructorDecl::inits()) before connecting
the redecl chain.  During those in-between imports structural eq fails
because the canonical decl is different.  This commit fixes this.
Synthesizing a test seemed extremely hard, however, Xerces analysis
reproduces the problem.

Reviewers: a_sidorin, a.sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, cfe-commits

Differential Revision: https://reviews.llvm.org/D53702

llvm-svn: 347306

1 files changed, 24 insertions, 19 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 8c80ecd1e67..fd8200c5653 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3144,19 +3144,6 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
         FromConstructor->isExplicit(),
         D->isInlineSpecified(), D->isImplicit(), D->isConstexpr()))
       return ToFunction;
-    if (unsigned NumInitializers = FromConstructor->getNumCtorInitializers()) {
-      SmallVector<CXXCtorInitializer *, 4> CtorInitializers(NumInitializers);
-      // Import first, then allocate memory and copy if there was no error.
-      if (Error Err = ImportContainerChecked(
-          FromConstructor->inits(), CtorInitializers))
-        return std::move(Err);
-      auto **Memory =
-          new (Importer.getToContext()) CXXCtorInitializer *[NumInitializers];
-      std::copy(CtorInitializers.begin(), CtorInitializers.end(), Memory);
-      auto *ToCtor = cast<CXXConstructorDecl>(ToFunction);
-      ToCtor->setCtorInitializers(Memory);
-      ToCtor->setNumCtorInitializers(NumInitializers);
-    }
   } else if (isa<CXXDestructorDecl>(D)) {
     if (GetImportedOrCreateDecl<CXXDestructorDecl>(
         ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
@@ -3184,6 +3171,30 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
       return ToFunction;
   }
 
+  // Connect the redecl chain.
+  if (FoundByLookup) {
+    auto *Recent = const_cast<FunctionDecl *>(
+          FoundByLookup->getMostRecentDecl());
+    ToFunction->setPreviousDecl(Recent);
+  }
+
+  // Import Ctor initializers.
+  if (auto *FromConstructor = dyn_cast<CXXConstructorDecl>(D)) {
+    if (unsigned NumInitializers = FromConstructor->getNumCtorInitializers()) {
+      SmallVector<CXXCtorInitializer *, 4> CtorInitializers(NumInitializers);
+      // Import first, then allocate memory and copy if there was no error.
+      if (Error Err = ImportContainerChecked(
+          FromConstructor->inits(), CtorInitializers))
+        return std::move(Err);
+      auto **Memory =
+          new (Importer.getToContext()) CXXCtorInitializer *[NumInitializers];
+      std::copy(CtorInitializers.begin(), CtorInitializers.end(), Memory);
+      auto *ToCtor = cast<CXXConstructorDecl>(ToFunction);
+      ToCtor->setCtorInitializers(Memory);
+      ToCtor->setNumCtorInitializers(NumInitializers);
+    }
+  }
+
   ToFunction->setQualifierInfo(ToQualifierLoc);
   ToFunction->setAccess(D->getAccess());
   ToFunction->setLexicalDeclContext(LexicalDC);
@@ -3199,12 +3210,6 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
   }
   ToFunction->setParams(Parameters);
 
-  if (FoundByLookup) {
-    auto *Recent = const_cast<FunctionDecl *>(
-          FoundByLookup->getMostRecentDecl());
-    ToFunction->setPreviousDecl(Recent);
-  }
-
   // We need to complete creation of FunctionProtoTypeLoc manually with setting
   // params it refers to.
   if (TInfo) {