Comment AST: Add support for variable templates

We treat them as variables of course, though if they have function
pointer type we treat them as functions, i.e. allow parameter and return
value specifications. Just like VarDecls.

Reviewed By: gribozavr2

Differential Revision: https://reviews.llvm.org/D111266

clang/include/clang/AST/Comment.h

@@ -1031,8 +1031,8 @@ struct DeclInfo {
     ClassKind,
 
     /// Something that we consider a "variable":
-    /// \li namespace scope variables;
-    /// \li static and non-static class data members;
+    /// \li namespace scope variables and variable templates;
+    /// \li static and non-static class data members and member templates;
     /// \li enumerators.
     VariableKind,
 

clang/lib/AST/Comment.cpp

@@ -294,6 +294,12 @@ void DeclInfo::fill() {
     Kind = ClassKind;
     break;
   case Decl::Var:
+    if (const VarTemplateDecl *VTD =
+            cast<VarDecl>(CommentDecl)->getDescribedVarTemplate()) {
+      TemplateKind = TemplateSpecialization;
+      TemplateParameters = VTD->getTemplateParameters();
+    }
+    LLVM_FALLTHROUGH;
   case Decl::Field:
   case Decl::EnumConstant:
   case Decl::ObjCIvar:
@@ -305,6 +311,15 @@ void DeclInfo::fill() {
       TSI = PD->getTypeSourceInfo();
     Kind = VariableKind;
     break;
+  case Decl::VarTemplate: {
+    const VarTemplateDecl *VTD = cast<VarTemplateDecl>(CommentDecl);
+    Kind = VariableKind;
+    TemplateKind = Template;
+    TemplateParameters = VTD->getTemplateParameters();
+    if (const VarDecl *VD = VTD->getTemplatedDecl())
+      TSI = VD->getTypeSourceInfo();
+    break;
+  }
   case Decl::Namespace:
     Kind = NamespaceKind;
     break;

clang/test/Sema/warn-documentation.cpp

@@ -1323,6 +1323,17 @@ namespace AllowParamAndReturnsOnFunctionPointerVars {
  */
 int (*functionPointerVariable)(int i);
 
+#if __cplusplus >= 201402L
+/**
+ * functionPointerVariableTemplate
+ *
+ * @param i is something.
+ * @returns integer.
+ */
+template<typename T>
+int (*functionPointerVariableTemplate)(T i);
+#endif
+
 struct HasFields {
   /**
    * functionPointerField
@@ -1331,6 +1342,18 @@ struct HasFields {
    * @returns integer.
    */
   int (*functionPointerField)(int i);
+
+#if __cplusplus >= 201402L
+  /**
+   * functionPointerTemplateMember
+   *
+   * @tparam T some type.
+   * @param i is integer.
+   * @returns integer.
+   */
+  template<typename T>
+  static int (*functionPointerTemplateMember)(int i);
+#endif
 };
 
 // expected-warning@+5 {{parameter 'p' not found in the function declaration}}
@@ -1343,6 +1366,23 @@ struct HasFields {
  */
 void (*functionPointerVariableThatLeadsNowhere)();
 
+#if __cplusplus >= 201402L
+// expected-warning@+8 {{template parameter 'X' not found in the template declaration}}
+// expected-note@+7 {{did you mean 'T'?}}
+// expected-warning@+7 {{parameter 'p' not found in the function declaration}}
+// expected-note@+6 {{did you mean 'x'?}}
+// expected-warning@+6 {{'\returns' command used in a comment that is attached to a function returning void}}
+/**
+ * functionPointerVariable
+ *
+ * \tparam X typo
+ * \param p not here.
+ * \returns integer.
+ */
+template<typename T>
+void (*functionPointerVariableTemplateThatLeadsNowhere)(T x);
+#endif
+
 // Still warn about param/returns commands for variables that don't specify
 // the type directly: