From 0fc095c775671b99f2a0d19fd198139766d13928 Mon Sep 17 00:00:00 2001
From: Slava Pestov <spestov@apple.com>
Date: Thu, 16 Jun 2016 03:17:57 -0700
Subject: [PATCH] Sema: Re-arrange deck chairs again

Another pre-emptive compiler_crasher regression fix.

I have an idea for consolidating some of these hacky circularity
checks in a nice way, but not now.
---
 lib/Sema/ITCDecl.cpp                          | 13 ++++++----
 lib/Sema/TypeCheckProtocol.cpp                | 24 ++++++++++++-------
 ...5-swift-typechecker-checkconformance.swift |  2 +-
 3 files changed, 24 insertions(+), 15 deletions(-)
 rename validation-test/{compiler_crashers => compiler_crashers_fixed}/28225-swift-typechecker-checkconformance.swift (88%)

diff --git a/lib/Sema/ITCDecl.cpp b/lib/Sema/ITCDecl.cpp
index 1371b77b31bc0..3c947e0593196 100644
--- a/lib/Sema/ITCDecl.cpp
+++ b/lib/Sema/ITCDecl.cpp
@@ -244,10 +244,6 @@ void IterativeTypeChecker::processInheritedProtocols(
   if (anyDependencies)
     return;
 
-  // FIXME: Hack to deal with recursion elsewhere.
-  if (protocol->isInheritedProtocolsValid())
-    return;
-
   // Check for circular inheritance.
   // FIXME: The diagnostics here should be improved... and this should probably
   // be handled by the normal cycle detection.
@@ -255,7 +251,8 @@ void IterativeTypeChecker::processInheritedProtocols(
   for (unsigned i = 0, n = allProtocols.size(); i != n; /*in loop*/) {
     if (allProtocols[i] == protocol ||
         allProtocols[i]->inheritsFrom(protocol)) {
-      if (!diagnosedCircularity) {
+      if (!diagnosedCircularity &&
+          !protocol->isInheritedProtocolsValid()) {
         diagnose(protocol,
                  diag::circular_protocol_def, protocol->getName().str());
         diagnosedCircularity = true;
@@ -269,6 +266,12 @@ void IterativeTypeChecker::processInheritedProtocols(
     ++i;
   }
 
+  // FIXME: Hack to deal with recursion elsewhere.
+  // We recurse through DeclContext::getLocalProtocols() -- this should be
+  // redone to use the IterativeDeclChecker also.
+  if (protocol->isInheritedProtocolsValid())
+    return;
+
   protocol->setInheritedProtocols(getASTContext().AllocateCopy(allProtocols));
 }
 
diff --git a/lib/Sema/TypeCheckProtocol.cpp b/lib/Sema/TypeCheckProtocol.cpp
index 5e1d1cc6849cb..e089ca42abc40 100644
--- a/lib/Sema/TypeCheckProtocol.cpp
+++ b/lib/Sema/TypeCheckProtocol.cpp
@@ -1807,15 +1807,21 @@ static Substitution getArchetypeSubstitution(TypeChecker &tc,
   SmallVector<ProtocolConformanceRef, 4> conformances;
 
   bool isError = replacement->is<ErrorType>();
-  for (auto proto : archetype->getConformsTo()) {
-    ProtocolConformance *conformance = nullptr;
-    bool conforms = tc.conformsToProtocol(replacement, proto, dc, None,
-                                          &conformance);
-    assert((conforms || isError) &&
-           "Conformance should already have been verified");
-    (void)isError;
-    (void)conforms;
-    conformances.push_back(ProtocolConformanceRef(proto, conformance));
+  assert((archetype != nullptr || isError) &&
+         "Should have built archetypes already");
+
+  // FIXME: Turn the nullptr check into an assertion
+  if (archetype != nullptr) {
+    for (auto proto : archetype->getConformsTo()) {
+      ProtocolConformance *conformance = nullptr;
+      bool conforms = tc.conformsToProtocol(replacement, proto, dc, None,
+                                            &conformance);
+      assert((conforms || isError) &&
+             "Conformance should already have been verified");
+      (void)isError;
+      (void)conforms;
+      conformances.push_back(ProtocolConformanceRef(proto, conformance));
+    }
   }
 
   return Substitution{
diff --git a/validation-test/compiler_crashers/28225-swift-typechecker-checkconformance.swift b/validation-test/compiler_crashers_fixed/28225-swift-typechecker-checkconformance.swift
similarity index 88%
rename from validation-test/compiler_crashers/28225-swift-typechecker-checkconformance.swift
rename to validation-test/compiler_crashers_fixed/28225-swift-typechecker-checkconformance.swift
index a73d33543d7f7..43860510f80f5 100644
--- a/validation-test/compiler_crashers/28225-swift-typechecker-checkconformance.swift
+++ b/validation-test/compiler_crashers_fixed/28225-swift-typechecker-checkconformance.swift
@@ -5,6 +5,6 @@
 // See http://swift.org/LICENSE.txt for license information
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -parse
+// RUN: not %target-swift-frontend %s -parse
 func e{enum k:A}protocol A{associatedtype B:A
 associatedtype n