Merge pull request swiftlang#74831 from slavapestov/fix-literal-regression-6.0

[6.0] AST: Fix substitution map composition edge case

Author: slavapestov

lib/AST/TypeSubstitution.cpp

@@ -227,7 +227,23 @@ operator()(CanType dependentType, Type conformingReplacementType,
         conformingReplacementType, conformedProtocol,
         /*allowMissing=*/true);
   }
-  return Subs.lookupConformance(dependentType, conformedProtocol);
+
+  auto result = Subs.lookupConformance(dependentType, conformedProtocol);
+  if (!result.isInvalid())
+    return result;
+
+  // Otherwise, the original type might be fixed to a concrete type in
+  // the substitution map's input generic signature.
+  if (auto genericSig = Subs.getGenericSignature()) {
+    if (genericSig->isValidTypeParameter(dependentType) &&
+        genericSig->isConcreteType(dependentType)) {
+      return conformedProtocol->getModuleContext()->lookupConformance(
+          conformingReplacementType, conformedProtocol,
+          /*allowMissing=*/true);
+    }
+  }
+
+  return ProtocolConformanceRef::forInvalid();
 }
 
 ProtocolConformanceRef MakeAbstractConformanceForGenericType::

test/SILGen/literal_expr_conditional_conformance.swift

@@ -0,0 +1,19 @@
+// RUN: %target-swift-emit-silgen %s
+
+public protocol P {
+  associatedtype A : Equatable
+}
+
+public struct G<A: Equatable>: P {}
+
+extension P where A == Int {
+  public init(integerLiteral: Int) {
+    fatalError()
+  }
+}
+
+extension G: ExpressibleByIntegerLiteral where A == Int {}
+
+public func f() -> G<Int> {
+  return 123
+}

validation-test/compiler_crashers_2_fixed/0022-rdar21625478.swift

@@ -1,11 +1,5 @@
 // RUN: %target-swift-frontend %s -emit-silgen
 
-// rdar://80395274 tracks getting this to pass with the requirement machine.
-// XFAIL: *
-
-// The test hangs in a noassert build:
-// REQUIRES: asserts
-
 import StdlibUnittest
 
 public struct MyRange<Bound : ForwardIndex> {