Merge pull request swiftlang#10144 from slavapestov/unbound-generic-types-part-infinity

Sema: Fix crash with unbound generic types in patterns

Author: slavapestov

lib/Sema/ConstraintSystem.cpp

@@ -1700,17 +1700,17 @@ Type simplifyTypeImpl(ConstraintSystem &cs, Type type, Fn getFixedTypeFn) {
         lookupBaseType = objectType;
       }
 
-      if (!lookupBaseType->mayHaveMembers()) return type;
-
-      auto subs = lookupBaseType->getContextSubstitutionMap(
+      if (lookupBaseType->mayHaveMembers()) {
+        auto subs = lookupBaseType->getContextSubstitutionMap(
           cs.DC->getParentModule(),
-          assocType->getDeclContext());
-      auto result = assocType->getDeclaredInterfaceType().subst(subs);
+            assocType->getDeclContext());
+        auto result = assocType->getDeclaredInterfaceType().subst(subs);
 
-      if (result)
-        return result;
+        if (result)
+          return result;
+      }
 
-      return DependentMemberType::get(ErrorType::get(newBase), assocType);
+      return DependentMemberType::get(lookupBaseType, assocType);
     }
 
     return type;

lib/Sema/TypeCheckPattern.cpp

@@ -869,6 +869,12 @@ bool TypeChecker::typeCheckPattern(Pattern *P, DeclContext *dc,
   case PatternKind::Typed: {
     TypedPattern *TP = cast<TypedPattern>(P);
     bool hadError = validateTypedPattern(*this, dc, TP, options, &resolver);
+
+    // If we have unbound generic types, don't apply them below; instead,
+    // the caller will call typeCheckBinding() later.
+    if (P->getType()->hasUnboundGenericType())
+      return hadError;
+
     Pattern *subPattern = TP->getSubPattern();
     if (coercePatternToType(subPattern, dc, P->getType(),
                             options|TR_FromNonInferredPattern, &resolver,

validation-test/compiler_crashers/28762-valuetype-hasunboundgenerictype-valuetype-hastypeparameter.swift renamed to validation-test/compiler_crashers_fixed/28762-valuetype-hasunboundgenerictype-valuetype-hastypeparameter.swift

@@ -6,5 +6,5 @@
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
 // REQUIRES: asserts
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 guard let f==A:UnfoldSequence