[CS] Handle conditional requirements in existential conversions of literals.

This likely affects other things too, but literals are where it appears
most. Previously, the mid-solving literal types like Array<$T0> were
just checked for whether they conformed to the protocol, without
acknowledging that this might introduce requirements on $T0, instead the
conditional requirements were checked against $T0, and so
failed (there's no reason that $T0 should satisfy the requirements at
all, it's a recently-constructed transient type variable). Instead,
capture the requirements and add them as constraints to the type
variable.

Fixes https://bugs.swift.org/browse/SR-7192 and rdar://problem/38461036
and improves https://bugs.swift.org/browse/SR-6941.

lib/Sema/CSSimplify.cpp

@@ -2580,7 +2580,8 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
   case ConstraintKind::SelfObjectOfProtocol:
     if (auto conformance =
           TC.containsProtocol(type, protocol, DC,
-                              ConformanceCheckFlags::InExpression)) {
+                              (ConformanceCheckFlags::InExpression|
+                               ConformanceCheckFlags::SkipConditionalRequirements))) {
       return recordConformance(*conformance);
     }
     break;

test/Generics/conditional_conformances_literals.swift

@@ -0,0 +1,130 @@
+// RUN: %target-typecheck-verify-swift -typecheck -verify
+
+// rdar://problem/38461036 , https://bugs.swift.org/browse/SR-7192 and highlights the real problem in https://bugs.swift.org/browse/SR-6941
+
+protocol SameType {}
+protocol Conforms {}
+
+struct Works: Hashable, Conforms {}
+struct Fails: Hashable {}
+
+extension Array: SameType where Element == Works {}
+extension Dictionary: SameType where Value == Works {}
+extension Array: Conforms where Element: Conforms {}
+extension Dictionary: Conforms where Value: Conforms {}
+
+let works = Works()
+let fails = Fails()
+
+func arraySameType() {
+    let arrayWorks = [works]
+    let arrayFails = [fails]
+
+    let _: SameType = [works]
+    let _: SameType = [fails]
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'SameType'}}
+
+    let _: SameType = arrayWorks
+    let _: SameType = arrayFails
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'SameType'}}
+
+    let _: SameType = [works] as [Works]
+    let _: SameType = [fails] as [Fails]
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'SameType'}}
+
+    let _: SameType = [works] as SameType
+    let _: SameType = [fails] as SameType
+    // expected-error@-1 {{'[Fails]' is not convertible to 'SameType'}}
+
+    let _: SameType = arrayWorks as SameType
+    let _: SameType = arrayFails as SameType
+    // expected-error@-1 {{'[Fails]' is not convertible to 'SameType'}}
+}
+
+func dictionarySameType() {
+    let dictWorks: [Int : Works] = [0 : works]
+    let dictFails: [Int : Fails] = [0 : fails]
+
+    let _: SameType = [0 : works]
+    let _: SameType = [0 : fails]
+    // expected-error@-1 {{contextual type 'SameType' cannot be used with dictionary literal}}
+
+    let _: SameType = dictWorks
+    let _: SameType = dictFails
+    // expected-error@-1 {{value of type '[Int : Fails]' does not conform to specified type 'SameType'}}
+
+    let _: SameType = [0 : works] as [Int : Works]
+    let _: SameType = [0 : fails] as [Int : Fails]
+    // expected-error@-1 {{value of type '[Int : Fails]' does not conform to specified type 'SameType'}}
+
+    let _: SameType = [0 : works] as SameType
+    let _: SameType = [0 : fails] as SameType
+    // expected-error@-1 {{'[Int : Fails]' is not convertible to 'SameType'}}
+
+    let _: SameType = dictWorks as SameType
+    let _: SameType = dictFails as SameType
+    // expected-error@-1 {{'[Int : Fails]' is not convertible to 'SameType'}}
+}
+
+func arrayConforms() {
+    let arrayWorks = [works]
+    let arrayFails = [fails]
+
+    let _: Conforms = [works]
+    let _: Conforms = [fails]
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = arrayWorks
+    let _: Conforms = arrayFails
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = [works] as [Works]
+    let _: Conforms = [fails] as [Fails]
+    // expected-error@-1 {{value of type '[Fails]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = [works] as Conforms
+    let _: Conforms = [fails] as Conforms
+    // expected-error@-1 {{'[Fails]' is not convertible to 'Conforms'}}
+
+    let _: Conforms = arrayWorks as Conforms
+    let _: Conforms = arrayFails as Conforms
+    // expected-error@-1 {{'[Fails]' is not convertible to 'Conforms'}}
+}
+
+func dictionaryConforms() {
+    let dictWorks: [Int : Works] = [0 : works]
+    let dictFails: [Int : Fails] = [0 : fails]
+
+    let _: Conforms = [0 : works]
+    let _: Conforms = [0 : fails]
+    // expected-error@-1 {{contextual type 'Conforms' cannot be used with dictionary literal}}
+
+    let _: Conforms = dictWorks
+    let _: Conforms = dictFails
+    // expected-error@-1 {{value of type '[Int : Fails]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = [0 : works] as [Int : Works]
+    let _: Conforms = [0 : fails] as [Int : Fails]
+    // expected-error@-1 {{value of type '[Int : Fails]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = [0 : works] as Conforms
+    let _: Conforms = [0 : fails] as Conforms
+    // expected-error@-1 {{'[Int : Fails]' is not convertible to 'Conforms'}}
+
+    let _: Conforms = dictWorks as Conforms
+    let _: Conforms = dictFails as Conforms
+    // expected-error@-1 {{'[Int : Fails]' is not convertible to 'Conforms'}}
+}
+
+func combined() {
+    let _: Conforms = [[0: [1 : [works]]]]
+    let _: Conforms = [[0: [1 : [fails]]]]
+    // expected-error@-1 {{value of type '[[Int : [Int : [Fails]]]]' does not conform to specified type 'Conforms'}}
+
+    // Needs self conforming protocols:
+    let _: Conforms = [[0: [1 : [works]] as Conforms]]
+    // expected-error@-1 {{value of type '[[Int : Conforms]]' does not conform to specified type 'Conforms'}}
+
+    let _: Conforms = [[0: [1 : [fails]] as Conforms]]
+    // expected-error@-1 {{'[Int : [Fails]]' is not convertible to 'Conforms'}}
+}