Don't allow function types that differ in SIL representation to be ma…

…tched by SameType constraint.

<rdar://problem/22181714> Crash when typing "signal"

Swift SVN r31594

lib/Sema/CSSimplify.cpp

@@ -914,6 +914,31 @@ static bool isFunctionTypeAcceptingNoArguments(Type type) {
   return true;
 }
 
+// Returns 'false' (i.e. no error) if it is legal to match functions with the
+// corresponding SIL function type representations and the given match kind.
+static bool matchFunctionSILRepresentations(SILFunctionTypeRepresentation rep1,
+                                            SILFunctionTypeRepresentation rep2,
+                                            TypeMatchKind kind) {
+  switch (kind) {
+  case TypeMatchKind::BindType:
+  case TypeMatchKind::BindToPointerType:
+  case TypeMatchKind::SameType:
+    return rep1 != rep2;
+
+  case TypeMatchKind::ConformsTo:
+    llvm_unreachable("Not sure if we can end up here");
+
+  case TypeMatchKind::Subtype:
+  case TypeMatchKind::Conversion:
+  case TypeMatchKind::ExplicitConversion:
+  case TypeMatchKind::ArgumentConversion:
+  case TypeMatchKind::ArgumentTupleConversion:
+  case TypeMatchKind::OperatorArgumentTupleConversion:
+  case TypeMatchKind::OperatorArgumentConversion:
+    return false;
+  }
+}
+
 ConstraintSystem::SolutionKind
 ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
                                      TypeMatchKind kind, unsigned flags,
@@ -984,6 +1009,12 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
     }
   }
 
+  if (matchFunctionSILRepresentations(
+        func1->getExtInfo().getSILRepresentation(),
+        func2->getExtInfo().getSILRepresentation(), kind)) {
+    return SolutionKind::Error;
+  }
+
   // Determine how we match up the input/result types.
   TypeMatchKind subKind;
   switch (kind) {

test/Parse/c_function_pointers.swift

@@ -42,4 +42,11 @@ if true {
   let k: @convention(c) () -> Int = S.staticMethod // expected-error{{}}
   let m: @convention(c) () -> Int = C.staticMethod // expected-error{{}}
   let n: @convention(c) () -> Int = C.classMethod // expected-error{{}}
+
+  // <rdar://problem/22181714> Crash when typing "signal"
+  let iuo_global: (() -> Int)! = global
+  let p: (@convention(c) () -> Int)! = iuo_global // expected-error{{a C function pointer can only be formed from a reference to a 'func' or a literal closure}}
+
+  func handler(callback: (@convention(c) () -> Int)!) {}
+  handler(iuo_global) // expected-error{{a C function pointer can only be formed from a reference to a 'func' or a literal closure}}
 }