[CSGen] Fix LinkedExprAnalyzer greedy operator linking

Let's not attempt to link arithmetic operators together in
presence of concrete and literal types.

Resolves: rdar://problem/35740653

Author: xedin

lib/Sema/CSGen.cpp

@@ -408,6 +408,11 @@ namespace {
       // argument types, we can directly simplify the associated constraint
       // graph.
       auto simplifyBinOpExprTyVars = [&]() {
+        // Don't attempt to do linking if there are
+        // literals intermingled with other inferred types.
+        if (lti.haveLiteral())
+          return;
+
         for (auto binExp1 : lti.binaryExprs) {
           for (auto binExp2 : lti.binaryExprs) {
             if (binExp1 == binExp2)

test/Constraints/operator.swift

@@ -176,3 +176,21 @@ func + (lhs: B_28688585, rhs: B_28688585) -> B_28688585 {
 
 let var_28688585 = D_28688585(value: 1)
 _ = var_28688585 + var_28688585 + var_28688585 // Ok
+
+// rdar://problem/35740653 - Fix `LinkedExprAnalyzer` greedy operator linking
+
+struct S_35740653 {
+  var v: Double = 42
+
+  static func value(_ value: Double) -> S_35740653 {
+    return S_35740653(v: value)
+  }
+
+  static func / (lhs: S_35740653, rhs: S_35740653) -> Double {
+     return lhs.v / rhs.v
+  }
+}
+
+func rdar35740653(val: S_35740653) {
+  let _ = 0...Int(val / .value(1.0 / 42.0)) // Ok
+}