[include-cleaner] Handle incomplete template specializations

Instantiation pattern is null for incomplete template types and using
specializaiton decl results in not seeing re-declarations.

Differential Revision: https://reviews.llvm.org/D148158

diff --git a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
index 25afdaa..e977bcb 100644 (file)
--- a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
+++ b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
@@ -21,6 +21,7 @@
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/Support/Casting.h"
@@ -81,9 +82,10 @@ class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
     if (llvm::isa_and_present<UsingShadowDecl, TypeAliasTemplateDecl>(ND))
       return ND;
     // This is the underlying decl used by TemplateSpecializationType, can be
-    // null when type is dependent if so fallback to primary template.
+    // null when type is dependent or not resolved to a pattern yet.
+    // If so, fallback to primary template.
     CXXRecordDecl *TD = TST->getAsCXXRecordDecl();
-    if (!TD)
+    if (!TD || TD->getTemplateSpecializationKind() == TSK_Undeclared)
       return ND;
     // We ignore explicit instantiations. This might imply marking the wrong
     // declaration as used in specific cases, but seems like the right trade-off

diff --git a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
index ad5bb0a..2060ffe 100644 (file)
--- a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
+++ b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
@@ -145,6 +145,9 @@ TEST(WalkAST, ClassTemplates) {
 
   // Implicit instantiations references most relevant template.
   EXPECT_THAT(
+      testWalk("template<typename> struct $explicit^Foo;", "^Foo<int> x();"),
+      ElementsAre(Decl::Kind::ClassTemplate));
+  EXPECT_THAT(
       testWalk("template<typename> struct $explicit^Foo {};", "^Foo<int> x;"),
       ElementsAre(Decl::CXXRecord));
   EXPECT_THAT(testWalk(R"cpp(
@@ -154,9 +157,15 @@ TEST(WalkAST, ClassTemplates) {
               ElementsAre(Decl::ClassTemplateSpecialization));
   EXPECT_THAT(testWalk(R"cpp(
     template<typename> struct Foo {};
-    template<typename T> struct $explicit^Foo<T*> { void x(); };)cpp",
+    template<typename T> struct $explicit^Foo<T*> {};)cpp",
                        "^Foo<int *> x;"),
               ElementsAre(Decl::ClassTemplatePartialSpecialization));
+  // Incomplete instantiations don't have a specific specialization associated.
+  EXPECT_THAT(testWalk(R"cpp(
+    template<typename> struct $explicit^Foo;
+    template<typename T> struct Foo<T*>;)cpp",
+                       "^Foo<int *> x();"),
+              ElementsAre(Decl::Kind::ClassTemplate));
   EXPECT_THAT(testWalk(R"cpp(
     template<typename> struct $explicit^Foo {};
     template struct Foo<int>;)cpp",