Fix completion involving overloaded static functions for templates

--------------------------------------------------------------------------
* https://reviews.llvm.org/D43453
--------------------------------------------------------------------------

Apply almost the same fix as D36390 but for templates.

Change-Id: I80b44d69898237f2f2b4310bc330120b7dfc49a8
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

2 files changed, 88 insertions, 40 deletions

diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index f2b1963df1..93b5070c83 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -6366,57 +6366,56 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
                                  bool FirstArgumentIsBase) {
   for (UnresolvedSetIterator F = Fns.begin(), E = Fns.end(); F != E; ++F) {
     NamedDecl *D = F.getDecl()->getUnderlyingDecl();
-    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
-      ArrayRef<Expr *> FunctionArgs = Args;
-      if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic()) {
-        QualType ObjectType;
-        Expr::Classification ObjectClassification;
-        if (Args.size() > 0) {
-          if (Expr *E = Args[0]) {
-            // Use the explit base to restrict the lookup:
-            ObjectType = E->getType();
-            ObjectClassification = E->Classify(Context);
-          } // .. else there is an implit base.
-          FunctionArgs = Args.slice(1);
-        }
-        AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
-                           cast<CXXMethodDecl>(FD)->getParent(), ObjectType,
-                           ObjectClassification, FunctionArgs, CandidateSet,
-                           SuppressUserConversions, PartialOverloading);
-      } else {
-        // Slice the first argument (which is the base) when we access
-        // static method as non-static
-        if (Args.size() > 0 && (!Args[0] || (FirstArgumentIsBase && isa<CXXMethodDecl>(FD) &&
-                                             !isa<CXXConstructorDecl>(FD)))) {
-          assert(cast<CXXMethodDecl>(FD)->isStatic());
-          FunctionArgs = Args.slice(1);
-        }
-        AddOverloadCandidate(FD, F.getPair(), FunctionArgs, CandidateSet,
-                             SuppressUserConversions, PartialOverloading);
-      }
-    } else {
-      FunctionTemplateDecl *FunTmpl = cast<FunctionTemplateDecl>(D);
-      if (isa<CXXMethodDecl>(FunTmpl->getTemplatedDecl()) &&
-          !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic()) {
-        QualType ObjectType;
-        Expr::Classification ObjectClassification;
+    ArrayRef<Expr *> FunctionArgs = Args;
+
+    FunctionTemplateDecl *FunTmpl = nullptr;
+    FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
+
+    const bool IsTemplate = FD ? false : true;
+    if (IsTemplate) {
+      FunTmpl = cast<FunctionTemplateDecl>(D);
+      FD = FunTmpl->getTemplatedDecl();
+    }
+
+    if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic()) {
+      QualType ObjectType;
+      Expr::Classification ObjectClassification;
+      if (Args.size() > 0) {
         if (Expr *E = Args[0]) {
           // Use the explit base to restrict the lookup:
           ObjectType = E->getType();
           ObjectClassification = E->Classify(Context);
         } // .. else there is an implit base.
+        FunctionArgs = Args.slice(1);
+      }
+      if (IsTemplate)
         AddMethodTemplateCandidate(
             FunTmpl, F.getPair(),
             cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
             ExplicitTemplateArgs, ObjectType, ObjectClassification,
-            Args.slice(1), CandidateSet, SuppressUserConversions,
+            FunctionArgs, CandidateSet, SuppressUserConversions,
             PartialOverloading);
-      } else {
-        AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
-                                     ExplicitTemplateArgs, Args,
-                                     CandidateSet, SuppressUserConversions,
-                                     PartialOverloading);
+      else
+        AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
+                           cast<CXXMethodDecl>(FD)->getParent(), ObjectType,
+                           ObjectClassification, FunctionArgs, CandidateSet,
+                           SuppressUserConversions, PartialOverloading);
+    } else {
+      // Slice the first argument (which is the base) when we access
+      // static method as non-static
+      if (Args.size() > 0 &&
+          (!Args[0] || (FirstArgumentIsBase && isa<CXXMethodDecl>(FD) &&
+                        !isa<CXXConstructorDecl>(FD)))) {
+        assert(cast<CXXMethodDecl>(FD)->isStatic());
+        FunctionArgs = Args.slice(1);
       }
+      if (IsTemplate)
+        AddTemplateOverloadCandidate(
+            FunTmpl, F.getPair(), ExplicitTemplateArgs, FunctionArgs,
+            CandidateSet, SuppressUserConversions, PartialOverloading);
+      else
+        AddOverloadCandidate(FD, F.getPair(), FunctionArgs, CandidateSet,
+                             SuppressUserConversions, PartialOverloading);
     }
   }
 }
diff --git a/test/Index/complete-call.cpp b/test/Index/complete-call.cpp
index ca116485ac..35f2009066 100644
--- a/test/Index/complete-call.cpp
+++ b/test/Index/complete-call.cpp
@@ -112,6 +112,33 @@ struct Bar2 : public Bar {
   }
 };
 
+struct BarTemplates {
+  static void foo_1() {}
+  void foo_1(float) {}
+  static void foo_1(int) {}
+
+  template<class T1, class T2>
+  static void foo_1(T1 a, T2 b) { a + b; }
+
+  template<class T1, class T2>
+  void foo_1(T1 a, T2 b, float c) { a + b + c; }
+
+  template<class T1, class T2>
+  static void foo_1(T2 a, int b, T1 c)  { a + b + c; }
+};
+
+void testTemplates() {
+  BarTemplates::foo_1();
+  BarTemplates b;
+  b.foo_1();
+}
+
+struct Bar2Template : public BarTemplates {
+  Bar2Template() {
+    BarTemplates::foo_1();
+  }
+};
+
 // RUN: c-index-test -code-completion-at=%s:47:9 %s | FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{RightParen )} (1)
 // CHECK-CC1: Completion contexts:
@@ -864,3 +891,25 @@ struct Bar2 : public Bar {
 // CHECK-CC62-NEXT: Nested name specifier
 // CHECK-CC62-NEXT: Objective-C interface
 
+// RUN: c-index-test -code-completion-at=%s:131:23 %s | FileCheck -check-prefix=CHECK-CC63 %s
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{RightParen )} (1)
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter float}{RightParen )} (1)
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter int}{RightParen )} (1)
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T1 a}{Comma , }{Placeholder T2 b}{RightParen )} (1)
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T1 a}{Comma , }{Placeholder T2 b}{Comma , }{Placeholder float c}{RightParen )} (1)
+// CHECK-CC63: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T2 a}{Comma , }{Placeholder int b}{Comma , }{Placeholder T1 c}{RightParen )} (1)
+
+// RUN: c-index-test -code-completion-at=%s:133:11 %s | FileCheck -check-prefix=CHECK-CC64 %s
+// CHECK-CC64: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{RightParen )} (1)
+// CHECK-CC64: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter float}{RightParen )} (1)
+// CHECK-CC64: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter int}{RightParen )} (1)
+// CHECK-CC64: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T1 a}{Comma , }{Placeholder T2 b}{RightParen )} (1)
+// CHECK-CC64: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T2 a}{Comma , }{Placeholder int b}{Comma , }{Placeholder T1 c}{RightParen )} (1)
+
+// RUN: c-index-test -code-completion-at=%s:138:25 %s | FileCheck -check-prefix=CHECK-CC65 %s
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{RightParen )} (1)
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter float}{RightParen )} (1)
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter int}{RightParen )} (1)
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T1 a}{Comma , }{Placeholder T2 b}{RightParen )} (1)
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T1 a}{Comma , }{Placeholder T2 b}{Comma , }{Placeholder float c}{RightParen )} (1)
+// CHECK-CC65: OverloadCandidate:{ResultType void}{Text foo_1}{LeftParen (}{CurrentParameter T2 a}{Comma , }{Placeholder int b}{Comma , }{Placeholder T1 c}{RightParen )} (1)