[CS] A couple of minor improvements to operator diagnostics

- Simplify the fix locator when looking for a
fix already present in a pattern match, this
avoids us emitting both a diagnostic for the
argument conversion, and for a conformance failure.
- Include tuples in the diagnostic logic where
we emit a generic "operator cannot be applied"
diagnostic, as a conformance diagnostic is
unlikely to be helpful in that case.

lib/Sema/CSDiagnostics.cpp

@@ -513,7 +513,10 @@ bool MissingConformanceFailure::diagnoseAsError() {
       llvm::SmallPtrSet<Expr *, 4> anchors;
       for (const auto *fix : getSolution().Fixes) {
         if (auto anchor = fix->getAnchor()) {
-          if (anchor.is<Expr *>())
+          auto path = fix->getLocator()->getPath();
+          SourceRange range;
+          simplifyLocator(anchor, path, range);
+          if (anchor && anchor.is<Expr *>())
             anchors.insert(getAsExpr(anchor));
         }
       }
@@ -654,10 +657,15 @@ bool MissingConformanceFailure::diagnoseAsAmbiguousOperatorRef() {
   if (!ODRE)
     return false;
 
-  auto name = ODRE->getDecls().front()->getBaseName();
-  if (!(name.isOperator() && getLHS()->isStdlibType() && getRHS()->isStdlibType()))
-    return false;
+  auto isStandardType = [](Type ty) {
+    return ty->isStdlibType() || ty->is<TupleType>();
+  };
 
+  auto name = ODRE->getDecls().front()->getBaseName();
+  if (!(name.isOperator() && isStandardType(getLHS()) &&
+        isStandardType(getRHS()))) {
+    return false;
+  }
   // If this is an operator reference and both types are from stdlib,
   // let's produce a generic diagnostic about invocation and a note
   // about missing conformance just in case.