[ResultBuilders] NFC: Support -debug-constraints{-on-line=} for declaration transforms

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -6510,6 +6510,9 @@ bool isResultBuilderMethodReference(ASTContext &, UnresolvedDotExpr *);
 unsigned getNumApplications(bool hasAppliedSelf,
                             FunctionRefInfo functionRefInfo);
 
+/// Determine whether the debug output is enabled for the given target.
+bool debugConstraintSolverForTarget(ASTContext &C,
+                                    SyntacticElementTarget target);
 } // end namespace constraints
 
 template<typename ...Args>

lib/Sema/BuilderTransform.cpp

@@ -962,6 +962,9 @@ TypeChecker::applyResultBuilderBodyTransform(FuncDecl *func, Type builderType) {
     return nullptr;
 
   ConstraintSystemOptions options = ConstraintSystemFlags::AllowFixes;
+  if (debugConstraintSolverForTarget(ctx, target))
+    options |= ConstraintSystemFlags::DebugConstraints;
+
   auto resultInterfaceTy = func->getResultInterfaceType();
   auto resultContextType = func->mapTypeIntoContext(resultInterfaceTy);
 

lib/Sema/CSSolver.cpp

@@ -1338,8 +1338,8 @@ void ConstraintSystem::shrink(Expr *expr) {
   }
 }
 
-static bool debugConstraintSolverForTarget(ASTContext &C,
-                                           SyntacticElementTarget target) {
+bool constraints::debugConstraintSolverForTarget(
+    ASTContext &C, SyntacticElementTarget target) {
   if (C.TypeCheckerOpts.DebugConstraintSolver)
     return true;