[AST] Adjust Diagnostic transaction to only track pending errors

Author: xedin

include/swift/AST/DiagnosticEngine.h

@@ -1058,10 +1058,19 @@ namespace swift {
       }
     }
 
-    bool hasDiagnostics() const {
-      return std::distance(Engine.TentativeDiagnostics.begin() +
-                               PrevDiagnostics,
-                           Engine.TentativeDiagnostics.end()) > 0;
+    bool hasErrors() const {
+      ArrayRef<Diagnostic> diagnostics(Engine.TentativeDiagnostics.begin() +
+                                           PrevDiagnostics,
+                                       Engine.TentativeDiagnostics.end());
+
+      for (auto &diagnostic : diagnostics) {
+        auto behavior = Engine.state.determineBehavior(diagnostic.getID());
+        if (behavior == DiagnosticState::Behavior::Fatal ||
+            behavior == DiagnosticState::Behavior::Error)
+          return true;
+      }
+
+      return false;
     }
 
     /// Abort and close this transaction and erase all diagnostics

lib/Sema/BuilderTransform.cpp

@@ -1719,7 +1719,7 @@ ConstraintSystem::matchFunctionBuilder(
     if (!applied)
       return getTypeMatchFailure(locator);
 
-    if (transaction.hasDiagnostics()) {
+    if (transaction.hasErrors()) {
       if (recordFix(
               IgnoreInvalidFunctionBuilderBody::duringConstraintGeneration(
                   *this, getConstraintLocator(fn.getBody()))))
@@ -1814,7 +1814,7 @@ class PreCheckFunctionBuilderApplication : public ASTWalker {
 
       HasError |= ConstraintSystem::preCheckExpression(
           E, DC, /*replaceInvalidRefsWithErrors=*/false);
-      HasError |= transaction.hasDiagnostics();
+      HasError |= transaction.hasErrors();
 
       if (SuppressDiagnostics)
         transaction.abort();

lib/Sema/CSFix.cpp

@@ -1588,7 +1588,7 @@ bool IgnoreInvalidFunctionBuilderBody::diagnose(const Solution &solution,
     }
 
     bool diagnosed() const {
-      return Transaction.hasDiagnostics();
+      return Transaction.hasErrors();
     }
   };