Merge pull request #58614 from ahoppen/pr/complete-type-with-same-type-requirement

[CodeCompletion] Offer suggestions if a nested type is followed by a same type requirement

Author: ahoppen

lib/Parse/ParseGeneric.cpp

@@ -350,9 +350,23 @@ ParserStatus Parser::parseGenericWhereClause(
         SecondType = makeParserResult(new (Context) ErrorTypeRepr(PreviousLoc));
 
       // Add the requirement
-      Requirements.push_back(RequirementRepr::getSameType(FirstType.get(),
-                                                      EqualLoc,
-                                                      SecondType.get()));
+      if (FirstType.hasCodeCompletion()) {
+        // If the first type has a code completion token, don't record a same
+        // type constraint because otherwise if we have
+        //   K.#^COMPLETE^# == Foo
+        // we parse this as
+        //   K == Foo
+        // and thus simplify K to Foo. But we didn't want to state that K is Foo
+        // but that K has a member of type Foo.
+        // FIXME: The proper way to fix this would be to represent the code
+        // completion token in the TypeRepr.
+        Requirements.push_back(RequirementRepr::getTypeConstraint(
+            FirstType.get(), EqualLoc,
+            new (Context) ErrorTypeRepr(SecondType.get()->getLoc())));
+      } else {
+        Requirements.push_back(RequirementRepr::getSameType(
+            FirstType.get(), EqualLoc, SecondType.get()));
+      }
     } else if (FirstType.hasCodeCompletion()) {
       // Recover by adding dummy constraint.
       Requirements.push_back(RequirementRepr::getTypeConstraint(

test/IDE/complete_where_clause.swift

@@ -41,6 +41,7 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=EXT_ASSOC_MEMBER_1 | %FileCheck %s -check-prefix=EXT_ASSOC_MEMBER
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=EXT_ASSOC_MEMBER_2 | %FileCheck %s -check-prefix=EXT_ASSOC_MEMBER
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=EXT_SECONDTYPE | %FileCheck %s -check-prefix=EXT_SECONDTYPE
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=WHERE_CLAUSE_WITH_EQUAL | %FileCheck %s -check-prefix=WHERE_CLAUSE_WITH_EQUAL
 
 class A1<T1, T2, T3> {}
 
@@ -264,3 +265,10 @@ extension WithAssoc where Int == #^EXT_SECONDTYPE^#
 // EXT_SECONDTYPE: Begin completions
 // EXT_SECONDTYPE-DAG: Decl[AssociatedType]/CurrNominal:   T;
 // EXT_SECONDTYPE: End completions
+
+func foo<K: WithAssoc>(_ key: K.Type) where K.#^WHERE_CLAUSE_WITH_EQUAL^# == S1 {}
+
+// WHERE_CLAUSE_WITH_EQUAL: Begin completions, 2 items
+// WHERE_CLAUSE_WITH_EQUAL-DAG: Decl[AssociatedType]/CurrNominal:   T;
+// WHERE_CLAUSE_WITH_EQUAL-DAG: Keyword/None:                       Type[#K.Type#];
+// WHERE_CLAUSE_WITH_EQUAL: End completions