From ecf814693819680911db46599ce1b51cc7446a0c Mon Sep 17 00:00:00 2001
From: Pavel Yaskevich <pyaskevich@apple.com>
Date: Thu, 29 Aug 2019 15:27:29 -0700
Subject: [PATCH] [Diagnostics] Treat type requirement failures associated with
 `Self` = `Any` as unrelated

This helps us to filter out cases like operator overloads where
`Self` type comes from e.g. default for collection element -
`[1, "hello"].map { $0 + 1 }`. Main problem here is that
collection type couldn't be determined without unification to
`Any` and `+` failing for all numeric overloads is just a consequence.
---
 lib/Sema/CSSimplify.cpp         | 19 ++++++++++++++++++-
 test/Constraints/closures.swift |  3 +--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/Sema/CSSimplify.cpp b/lib/Sema/CSSimplify.cpp
index d9fbb390c33..d075cba5318 100644
--- a/lib/Sema/CSSimplify.cpp
+++ b/lib/Sema/CSSimplify.cpp
@@ -3832,8 +3832,8 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
                                  ConstraintKind kind,
                                  ConstraintLocatorBuilder locator,
                                  TypeMatchOptions flags) {
+  auto *typeVar = type->getAs<TypeVariableType>();
   if (shouldAttemptFixes()) {
-    auto *typeVar = type->getAs<TypeVariableType>();
     // If type variable, associated with this conformance check,
     // has been determined to be a "hole" in constraint system,
     // let's consider this check a success without recording
@@ -3983,6 +3983,23 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
       return SolutionKind::Error;
 
     if (path.back().is<LocatorPathElt::AnyRequirement>()) {
+      // If this is a requirement associated with `Self` which is bound
+      // to `Any`, let's consider this "too incorrect" to continue.
+      //
+      // This helps us to filter out cases like operator overloads where
+      // `Self` type comes from e.g. default for collection element -
+      // `[1, "hello"].map { $0 + 1 }`. Main problem here is that
+      // collection type couldn't be determined without unification to
+      // `Any` and `+` failing for all numeric overloads is just a consequence.
+      if (typeVar && type->isAny()) {
+        auto *GP = typeVar->getImpl().getGenericParameter();
+        if (auto *GPD = GP->getDecl()) {
+          auto *DC = GPD->getDeclContext();
+          if (DC->isTypeContext() && DC->getSelfInterfaceType()->isEqual(GP))
+            return SolutionKind::Error;
+        }
+      }
+
       if (auto *fix =
               fixRequirementFailure(*this, type, protocolTy, anchor, path)) {
         if (!recordFix(fix)) {
diff --git a/test/Constraints/closures.swift b/test/Constraints/closures.swift
index 389ad93b178..9530c3c1ce3 100644
--- a/test/Constraints/closures.swift
+++ b/test/Constraints/closures.swift
@@ -182,8 +182,7 @@ func r22162441(_ lines: [String]) {
 
 func testMap() {
   let a = 42
-  [1,a].map { $0 + 1.0 } // expected-error {{binary operator '+' cannot be applied to operands of type 'Any' and 'Double'}}
-  // expected-note @-1 {{expected an argument list of type '(Double, Double)'}}
+  [1,a].map { $0 + 1.0 } // expected-error {{cannot convert value of type 'Int' to expected element type 'Double'}}
 }
 
 // <rdar://problem/22414757> "UnresolvedDot" "in wrong phase" assertion from verifier