Make matchFunctionTypes take a callback to match parameter and result types.

Author: rudkx

lib/AST/Type.cpp

@@ -2178,14 +2178,10 @@ namespace {
   };
 } // end anonymous namespace
 
-static bool matches(CanType t1, CanType t2, TypeMatchOptions matchMode,
-                    ParameterPosition paramPosition,
-                    OptionalUnwrapping insideOptional);
-
 static bool matchFunctionTypes(CanAnyFunctionType fn1, CanAnyFunctionType fn2,
                                TypeMatchOptions matchMode,
-                               ParameterPosition paramPosition,
-                               OptionalUnwrapping insideOptional) {
+                               OptionalUnwrapping insideOptional,
+                               std::function<bool()> paramsAndResultMatch) {
   // FIXME: Handle generic functions in non-ABI matches.
   if (!matchMode.contains(TypeMatchFlags::AllowABICompatible)) {
     if (!isa<FunctionType>(fn1) || !isa<FunctionType>(fn2))
@@ -2214,11 +2210,7 @@ static bool matchFunctionTypes(CanAnyFunctionType fn1, CanAnyFunctionType fn2,
   if (ext1 != ext2)
     return false;
 
-  // Inputs are contravariant, results are covariant.
-  return (matches(fn2.getInput(), fn1.getInput(), matchMode,
-                  ParameterPosition::Parameter, OptionalUnwrapping::None) &&
-          matches(fn1.getResult(), fn2.getResult(), matchMode,
-                  ParameterPosition::NotParameter, OptionalUnwrapping::None));
+  return paramsAndResultMatch();
 }
 
 static bool matches(CanType t1, CanType t2, TypeMatchOptions matchMode,
@@ -2298,8 +2290,17 @@ static bool matches(CanType t1, CanType t2, TypeMatchOptions matchMode,
     if (!fn1)
       return false;
 
-    return matchFunctionTypes(fn1, fn2, matchMode, paramPosition,
-                              insideOptional);
+    std::function<bool()> paramsAndResultMatch = [=]() {
+      // Inputs are contravariant, results are covariant.
+      return (matches(fn2.getInput(), fn1.getInput(), matchMode,
+                      ParameterPosition::Parameter, OptionalUnwrapping::None) &&
+              matches(fn1.getResult(), fn2.getResult(), matchMode,
+                      ParameterPosition::NotParameter,
+                      OptionalUnwrapping::None));
+    };
+
+    return matchFunctionTypes(fn1, fn2, matchMode, insideOptional,
+                              paramsAndResultMatch);
   }
 
   if (matchMode.contains(TypeMatchFlags::AllowNonOptionalForIUOParam) &&