[CSOptimizer] Don't optimize (implicit) calls with code completion arguments

`containsIDEInspectionTarget` doesn't work for implicit argument
lists, but luckily implicit code completion expressions cannot
be injected into arguments, so we can check whether whether they
appear at an argument position and prevent optimization.

Author: xedin

lib/Sema/CSOptimizer.cpp

@@ -167,9 +167,18 @@ static Constraint *determineBestChoicesInContext(
         applicableFn.get()->getFirstType()->getAs<FunctionType>();
 
     auto argumentList = cs.getArgumentList(applicableFn.get()->getLocator());
-    if (!argumentList || cs.containsIDEInspectionTarget(argumentList))
+    if (!argumentList)
       return nullptr;
 
+    for (const auto &argument : *argumentList) {
+      if (auto *expr = argument.getExpr()) {
+        // Directly `<#...#>` or has one inside.
+        if (isa<CodeCompletionExpr>(expr) ||
+            cs.containsIDEInspectionTarget(expr))
+          return nullptr;
+      }
+    }
+
     SmallVector<FunctionType::Param, 8> argsWithLabels;
     {
       argsWithLabels.append(argFuncType->getParams().begin(),

test/IDE/complete_operators.swift

@@ -52,7 +52,7 @@ func testPostfix6() {
 func testPostfix7() {
   1 + 2 * 3.0#^POSTFIX_7^#
 }
-// POSTFIX_7: Decl[PostfixOperatorFunction]/CurrModule:  ***[#Double#]
+// POSTFIX_7: Decl[PostfixOperatorFunction]/CurrModule/TypeRelation[Convertible]:  ***[#Double#]
 
 func testPostfix8(x: S) {
   x#^POSTFIX_8^#