From: Balazs Keri <1.int32@gmail.com>
Date: Wed, 7 Aug 2019 12:40:17 +0000 (+0000)
Subject: [ASTImporter] Do not import FunctionTemplateDecl in record twice.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4dedb042153e0f654914ff1d9bf618ed016bf7b8;p=clang

[ASTImporter] Do not import FunctionTemplateDecl in record twice.

Summary:
For functions there is a check to not duplicate the declaration if it is in a
record (class). For function templates there was no similar check, if a
template (in the same class) was imported multiple times the
FunctionTemplateDecl was created multiple times with the same templated
FunctionDecl. This can result in problems with the declaration chain.

Reviewers: martong, a.sidorin, shafik, a_sidorin

Reviewed By: a_sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65203

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@368163 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index d7789a99a5..8ecbad3c68 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -3118,9 +3118,19 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
   if (FoundByLookup) {
     if (isa<CXXMethodDecl>(FoundByLookup)) {
       if (D->getLexicalDeclContext() == D->getDeclContext()) {
-        if (!D->doesThisDeclarationHaveABody())
+        if (!D->doesThisDeclarationHaveABody()) {
+          if (FunctionTemplateDecl *DescribedD =
+                  D->getDescribedFunctionTemplate()) {
+            // Handle a "templated" function together with its described
+            // template. This avoids need for a similar check at import of the
+            // described template.
+            assert(FoundByLookup->getDescribedFunctionTemplate() &&
+                   "Templated function mapped to non-templated?");
+            Importer.MapImported(DescribedD,
+                                 FoundByLookup->getDescribedFunctionTemplate());
+          }
           return Importer.MapImported(D, FoundByLookup);
-        else {
+        } else {
           // Let's continue and build up the redecl chain in this case.
           // FIXME Merge the functions into one decl.
         }
diff --git a/unittests/AST/ASTImporterTest.cpp b/unittests/AST/ASTImporterTest.cpp
index 07beccefbc..151b279b9b 100644
--- a/unittests/AST/ASTImporterTest.cpp
+++ b/unittests/AST/ASTImporterTest.cpp
@@ -2389,6 +2389,49 @@ TEST_P(ImportFunctions,
                 functionDecl(hasName("f"), hasDescendant(declRefExpr()))))));
 }
 
+struct ImportFunctionTemplates : ASTImporterOptionSpecificTestBase {};
+
+TEST_P(ImportFunctionTemplates, ImportFunctionTemplateInRecordDeclTwice) {
+  auto Code =
+      R"(
+      class X {
+        template <class T>
+        void f(T t);
+      };
+      )";
+  Decl *FromTU1 = getTuDecl(Code, Lang_CXX, "input1.cc");
+  auto *FromD1 = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      FromTU1, functionTemplateDecl(hasName("f")));
+  auto *ToD1 = Import(FromD1, Lang_CXX);
+  Decl *FromTU2 = getTuDecl(Code, Lang_CXX, "input2.cc");
+  auto *FromD2 = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      FromTU2, functionTemplateDecl(hasName("f")));
+  auto *ToD2 = Import(FromD2, Lang_CXX);
+  EXPECT_EQ(ToD1, ToD2);
+}
+
+TEST_P(ImportFunctionTemplates,
+       ImportFunctionTemplateWithDefInRecordDeclTwice) {
+  auto Code =
+      R"(
+      class X {
+        template <class T>
+        void f(T t);
+      };
+      template <class T>
+      void X::f(T t) {};
+      )";
+  Decl *FromTU1 = getTuDecl(Code, Lang_CXX, "input1.cc");
+  auto *FromD1 = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      FromTU1, functionTemplateDecl(hasName("f")));
+  auto *ToD1 = Import(FromD1, Lang_CXX);
+  Decl *FromTU2 = getTuDecl(Code, Lang_CXX, "input2.cc");
+  auto *FromD2 = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      FromTU2, functionTemplateDecl(hasName("f")));
+  auto *ToD2 = Import(FromD2, Lang_CXX);
+  EXPECT_EQ(ToD1, ToD2);
+}
+
 struct ImportFriendFunctions : ImportFunctions {};
 
 TEST_P(ImportFriendFunctions, ImportFriendFunctionRedeclChainProto) {
@@ -5223,6 +5266,9 @@ INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFriendFunctionTemplates,
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportClasses,
                         DefaultTestValuesForRunOptions, );
 
+INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFunctionTemplates,
+                        DefaultTestValuesForRunOptions, );
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFriendFunctions,
                         DefaultTestValuesForRunOptions, );