[CodeCompletion] Completion support for static subscript

lib/IDE/CodeCompletion.cpp

@@ -2594,8 +2594,8 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
   }
 
   void addSubscriptCall(const SubscriptDecl *SD, DeclVisibilityKind Reason) {
-    // Don't add subscript call to meta types.
-    if (!ExprType || ExprType->is<AnyMetatypeType>())
+    // Don't add subscript call to unqualified completion.
+    if (!ExprType)
       return;
 
     // Subscript after '.' is valid only after type part of Swift keypath

lib/IDE/ExprContextAnalysis.cpp

@@ -268,6 +268,7 @@ class ExprParentFinder : public ASTWalker {
 static void collectPossibleCalleesByQualifiedLookup(
     DeclContext &DC, Type baseTy, DeclBaseName name,
     SmallVectorImpl<FunctionTypeAndDecl> &candidates) {
+  bool isOnMetaType = baseTy->is<AnyMetatypeType>();
 
   SmallVector<ValueDecl *, 2> decls;
   auto resolver = DC.getASTContext().getLazyResolver();
@@ -287,16 +288,18 @@ static void collectPossibleCalleesByQualifiedLookup(
       continue;
     Type declaredMemberType = VD->getInterfaceType();
     if (VD->getDeclContext()->isTypeContext()) {
-      if (auto *FD = dyn_cast<FuncDecl>(VD)) {
-        if (!baseTy->is<AnyMetatypeType>())
+      if (isa<FuncDecl>(VD)) {
+        if (!isOnMetaType)
           declaredMemberType =
               declaredMemberType->castTo<AnyFunctionType>()->getResult();
-      }
-      if (auto *CD = dyn_cast<ConstructorDecl>(VD)) {
-        if (!baseTy->is<AnyMetatypeType>())
+      } else if (isa<ConstructorDecl>(VD)) {
+        if (!isOnMetaType)
           continue;
         declaredMemberType =
             declaredMemberType->castTo<AnyFunctionType>()->getResult();
+      } else if (isa<SubscriptDecl>(VD)) {
+        if (isOnMetaType != VD->isStatic())
+          continue;
       }
     }
 

lib/Sema/LookupVisibleDecls.cpp

@@ -142,6 +142,17 @@ static bool isDeclVisibleInLookupMode(ValueDecl *Member, LookupState LS,
     // Otherwise, either call a function or curry it.
     return true;
   }
+  if (auto *SD = dyn_cast<SubscriptDecl>(Member)) {
+    // Cannot use static subscripts on non-metatypes.
+    if (!LS.isOnMetatype() && SD->isStatic())
+      return false;
+
+    // Cannot use instance subscript on metatypes.
+    if (LS.isOnMetatype() && !SD->isStatic() && !LS.isIncludingInstanceMembers())
+      return false;
+
+    return true;
+  }
   if (auto *VD = dyn_cast<VarDecl>(Member)) {
     // Cannot use static properties on non-metatypes.
     if (!(LS.isQualified() && LS.isOnMetatype()) && VD->isStatic())

test/IDE/complete_subscript.swift

@@ -0,0 +1,67 @@
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=METATYPE_UNRESOLVED | %FileCheck %s -check-prefix=METATYPE_UNRESOLVED
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=METATYPE_INT | %FileCheck %s -check-prefix=METATYPE_INT
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INSTANCE_INT | %FileCheck %s -check-prefix=INSTANCE_INT
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=METATYPE_ARCHETYPE | %FileCheck %s -check-prefix=METATYPE_ARCHETYPE
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INSTANCE_ARCHETYPE | %FileCheck %s -check-prefix=INSTANCE_ARCHETYPE
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=METATYPE_LABEL | %FileCheck %s -check-prefix=METATYPE_LABEL
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INSTANCE_LABEL  | %FileCheck %s -check-prefix=INSTANCE_LABEL
+
+struct MyStruct<T> {
+  static subscript(x: Int, static defValue: T) -> MyStruct<T> {
+    fatalError()
+  }
+  subscript(x: Int, instance defValue: T) -> Int {
+    fatalError()
+  }
+}
+
+func test1() {
+  let _ = MyStruct #^METATYPE_UNRESOLVED^#
+// METATYPE_UNRESOLVED: Begin completions, 4 items
+// METATYPE_UNRESOLVED-DAG: Decl[Subscript]/CurrNominal:        [{#(x): Int#}, {#static: _#}][#MyStruct<_>#];
+// METATYPE_UNRESOLVED-DAG: Decl[Constructor]/CurrNominal:      ()[#MyStruct<_>#];
+// METATYPE_UNRESOLVED-DAG: Keyword[self]/CurrNominal:          .self[#MyStruct<_>.Type#];
+// METATYPE_UNRESOLVED-DAG: Keyword/CurrNominal:                .Type[#MyStruct<_>.Type#];
+// METATYPE_UNRESOLVED: End completions
+
+
+  let _ = MyStruct<Int> #^METATYPE_INT^#
+// METATYPE_INT: Begin completions, 4 items
+// METATYPE_INT-DAG: Decl[Subscript]/CurrNominal:        [{#(x): Int#}, {#static: Int#}][#MyStruct<Int>#];
+// METATYPE_INT-DAG: Decl[Constructor]/CurrNominal:      ()[#MyStruct<Int>#];
+// METATYPE_INT-DAG: Keyword[self]/CurrNominal:          .self[#MyStruct<Int>.Type#];
+// METATYPE_INT-DAG: Keyword/CurrNominal:                .Type[#MyStruct<Int>.Type#];
+// METATYPE_INT: End completions
+
+  let _ = MyStruct<Int>()#^INSTANCE_INT^#
+// INSTANCE_INT: Begin completions, 2 items
+// INSTANCE_INT-DAG: Decl[Subscript]/CurrNominal:        [{#(x): Int#}, {#instance: Int#}][#Int#];
+// INSTANCE_INT-DAG: Keyword[self]/CurrNominal:          .self[#MyStruct<Int>#];
+// INSTANCE_INT: End completions
+
+}
+func test2<U>(value: MyStruct<U>) {
+  let _ = MyStruct<U>#^METATYPE_ARCHETYPE^#
+// METATYPE_ARCHETYPE: Begin completions, 4 items
+// METATYPE_ARCHETYPE-DAG: Decl[Subscript]/CurrNominal:        [{#(x): Int#}, {#static: U#}][#MyStruct<U>#];
+// METATYPE_ARCHETYPE-DAG: Decl[Constructor]/CurrNominal:      ()[#MyStruct<U>#];
+// METATYPE_ARCHETYPE-DAG: Keyword[self]/CurrNominal:          .self[#MyStruct<U>.Type#];
+// METATYPE_ARCHETYPE-DAG: Keyword/CurrNominal:                .Type[#MyStruct<U>.Type#];
+// METATYPE_ARCHETYPE: End completions
+
+  let _ = value #^INSTANCE_ARCHETYPE^#
+// INSTANCE_ARCHETYPE: Begin completions, 2 items
+// INSTANCE_ARCHETYPE-DAG: Decl[Subscript]/CurrNominal:        [{#(x): Int#}, {#instance: U#}][#Int#];
+// INSTANCE_ARCHETYPE-DAG: Keyword[self]/CurrNominal:          .self[#MyStruct<U>#];
+// INSTANCE_ARCHETYPE: End completions
+
+  let _ = MyStruct<U>[42, #^METATYPE_LABEL^#
+// METATYPE_LABEL: Begin completions, 1 items
+// METATYPE_LABEL-DAG: Keyword/ExprSpecific:               static: [#Argument name#];
+// METATYPE_LABEL: End completions
+
+  let _ = value[42, #^INSTANCE_LABEL^#
+// INSTANCE_LABEL: Begin completions, 1 items
+// INSTANCE_LABEL-DAG: Keyword/ExprSpecific:               instance: [#Argument name#];
+// INSTANCE_LABEL: End completions
+}