Merge pull request #60387 from amritpan/improve-solution-printing

[ConstraintSystem] Improve solution printing in the type inference algorithm debug output

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -946,6 +946,10 @@ struct AppliedBuilderTransform {
   Expr *returnExpr = nullptr;
 };
 
+struct Score;
+/// Display a score.
+llvm::raw_ostream &operator<<(llvm::raw_ostream &out, const Score &score);
+
 /// Describes the fixed score of a solution to the constraint system.
 struct Score {
   unsigned Data[NumScoreKinds] = {};
@@ -1016,11 +1020,94 @@ struct Score {
   friend bool operator>=(const Score &x, const Score &y) {
     return !(x < y);
   }
+  
+  /// Return ScoreKind descriptions for printing alongside non-zero ScoreKinds
+  /// in debug output.
+  static std::string getNameFor(ScoreKind kind) {
+    switch (kind) {
+    case SK_Hole:
+      return "hole";
 
-};
+    case SK_Unavailable:
+      return "use of an unavailable declaration";
 
-/// Display a score.
-llvm::raw_ostream &operator<<(llvm::raw_ostream &out, const Score &score);
+    case SK_AsyncInSyncMismatch:
+      return "async-in-synchronous mismatch";
+
+    case SK_SyncInAsync:
+      return "sync-in-asynchronous";
+
+    case SK_ForwardTrailingClosure:
+      return "forward scan when matching a trailing closure";
+
+    case SK_Fix:
+      return "applied fix";
+
+    case SK_DisfavoredOverload:
+      return "disfavored overload";
+
+    case SK_UnresolvedMemberViaOptional:
+      return "unwrapping optional at unresolved member base";
+
+    case SK_ForceUnchecked:
+      return "force of an implicitly unwrapped optional";
+
+    case SK_UserConversion:
+      return "user conversion";
+
+    case SK_FunctionConversion:
+      return "function conversion";
+
+    case SK_NonDefaultLiteral:
+      return "non-default literal";
+
+    case SK_CollectionUpcastConversion:
+      return "collection upcast conversion";
+
+    case SK_ValueToOptional:
+      return "value to optional promotion";
+
+    case SK_EmptyExistentialConversion:
+      return "empty-existential conversion";
+
+    case SK_KeyPathSubscript:
+      return "key path subscript";
+
+    case SK_ValueToPointerConversion:
+      return "value-to-pointer conversion";
+
+    case SK_FunctionToAutoClosureConversion:
+      return "function to autoclosure parameter conversion";
+
+    case SK_ImplicitValueConversion:
+      return "value-to-value conversion";
+
+    case SK_UnappliedFunction:
+      return "use of overloaded unapplied function";
+    }
+  }
+
+  /// Print Score list a with brief description of any non-zero ScoreKinds.
+  void print(llvm::raw_ostream &out) const {
+    bool hasNonDefault = false;
+    for (unsigned int i = 0; i < NumScoreKinds; ++i) {
+      if (Data[i] != 0) {
+        out << " [";
+        out << getNameFor(ScoreKind(i));
+        out << "(s) = ";
+        out << std::to_string(Data[i]);
+        out << "]";
+        hasNonDefault = true;
+      }
+    }
+
+    if (!hasNonDefault) {
+      out << " <default ";
+      out << *this;
+      out << ">";
+    }
+  }
+};
 
 /// Describes a dependent type that has been opened to a particular type
 /// variable.

include/swift/Sema/OverloadChoice.h

@@ -310,6 +310,9 @@ class OverloadChoice {
     assert(isDecl() && "only makes sense for declaration choices");
     return TheFunctionRefKind;
   }
+
+  /// Print selected overload choice kind found for Solution in debug output.
+  void dump(Type adjustedOpenedType, SourceManager *sm, raw_ostream &out) const;
 };
 
 } // end namespace constraints

lib/Sema/CSApply.cpp

@@ -9124,9 +9124,9 @@ ExprWalker::rewriteTarget(SolutionApplicationTarget target) {
 
       auto &log = llvm::errs();
       if (isPartial) {
-        log << "---Partially type-checked expression---\n";
+        log << "\n---Partially type-checked expression---\n";
       } else {
-        log << "---Type-checked expression---\n";
+        log << "\n---Type-checked expression---\n";
       }
       resultExpr->dump(log);
       log << "\n";
@@ -9204,7 +9204,7 @@ Optional<SolutionApplicationTarget> ConstraintSystem::applySolution(
     auto node = target.getAsASTNode();
     if (node && needsPostProcessing) {
       auto &log = llvm::errs();
-      log << "---Fully type-checked target---\n";
+      log << "\n---Fully type-checked target---\n";
       node.dump(log);
       log << "\n";
     }

lib/Sema/CSRanking.cpp

@@ -32,70 +32,6 @@ using namespace constraints;
 #define DEBUG_TYPE "Constraint solver overall"
 STATISTIC(NumDiscardedSolutions, "Number of solutions discarded");
 
-static StringRef getScoreKindName(ScoreKind kind) {
-  switch (kind) {
-  case SK_Hole:
-    return "hole in the constraint system";
-
-  case SK_Unavailable:
-    return "use of an unavailable declaration";
-
-  case SK_AsyncInSyncMismatch:
-    return "async-in-synchronous mismatch";
-
-  case SK_SyncInAsync:
-    return "sync-in-asynchronous";
-
-  case SK_ForwardTrailingClosure:
-    return "forward scan when matching a trailing closure";
-
-  case SK_Fix:
-    return "attempting to fix the source";
-
-  case SK_DisfavoredOverload:
-    return "disfavored overload";
-
-  case SK_UnresolvedMemberViaOptional:
-    return "unwrapping optional at unresolved member base";
-
-  case SK_ForceUnchecked:
-    return "force of an implicitly unwrapped optional";
-
-  case SK_UserConversion:
-    return "user conversion";
-
-  case SK_FunctionConversion:
-    return "function conversion";
-
-  case SK_NonDefaultLiteral:
-    return "non-default literal";
-
-  case SK_CollectionUpcastConversion:
-    return "collection upcast conversion";
-
-  case SK_ValueToOptional:
-    return "value to optional";
-
-  case SK_EmptyExistentialConversion:
-    return "empty-existential conversion";
-
-  case SK_KeyPathSubscript:
-    return "key path subscript";
-
-  case SK_ValueToPointerConversion:
-    return "value-to-pointer conversion";
-
-  case SK_FunctionToAutoClosureConversion:
-    return "function to autoclosure parameter";
-
-  case SK_ImplicitValueConversion:
-    return "value-to-value conversion";
-
-  case SK_UnappliedFunction:
-    return "overloaded unapplied function";
-  }
-}
-
 void ConstraintSystem::increaseScore(ScoreKind kind, unsigned value) {
   if (isForCodeCompletion()) {
     switch (kind) {
@@ -119,7 +55,8 @@ void ConstraintSystem::increaseScore(ScoreKind kind, unsigned value) {
   if (isDebugMode() && value > 0) {
     if (solverState)
       llvm::errs().indent(solverState->depth * 2);
-    llvm::errs() << "(increasing score due to " << getScoreKindName(kind) << ")\n";
+    llvm::errs() << "(increasing '" << Score::getNameFor(kind) << "' score by "  << value 
+                 << ")\n";
   }
 
   unsigned index = static_cast<unsigned>(kind);
@@ -1420,7 +1357,7 @@ ConstraintSystem::findBestSolution(SmallVectorImpl<Solution> &viable,
 
     for (unsigned i = 0, n = viable.size(); i != n; ++i) {
       llvm::errs().indent(solverState->depth * 2)
-          << "--- Solution #" << i << " ---\n";
+          << "\n--- Solution #" << i << " ---\n";
       viable[i].dump(llvm::errs().indent(solverState->depth * 2));
     }
   }

lib/Sema/CSSolver.cpp

@@ -790,7 +790,7 @@ bool ConstraintSystem::Candidate::solve(
       log << "--- Solutions ---\n";
       for (unsigned i = 0, n = solutions.size(); i != n; ++i) {
         auto &solution = solutions[i];
-        log << "--- Solution #" << i << " ---\n";
+        log << "\n--- Solution #" << i << " ---\n";
         solution.dump(log);
       }
     }
@@ -1275,12 +1275,12 @@ Optional<std::vector<Solution>> ConstraintSystem::solve(
     // Debug-print the set of solutions.
     if (isDebugMode()) {
       if (result.getKind() == SolutionResult::Success) {
-        llvm::errs() << "---Solution---\n";
+        llvm::errs() << "\n---Solution---\n";
         result.getSolution().dump(llvm::errs());
       } else if (result.getKind() == SolutionResult::Ambiguous) {
         auto solutions = result.getAmbiguousSolutions();
         for (unsigned i : indices(solutions)) {
-          llvm::errs() << "--- Solution #" << i << " ---\n";
+          llvm::errs() << "\n--- Solution #" << i << " ---\n";
           solutions[i].dump(llvm::errs());
         }
       }
@@ -1418,7 +1418,7 @@ bool ConstraintSystem::solve(SmallVectorImpl<Solution> &solutions,
 
   if (isDebugMode()) {
     auto &log = llvm::errs();
-    log << "---Solver statistics---\n";
+    log << "\n---Solver statistics---\n";
     log << "Total number of scopes explored: " << solverState->NumStatesExplored << "\n";
     log << "Maximum depth reached while exploring solutions: " << solverState->maxDepth << "\n";
     if (Timer) {

lib/Sema/CSStep.cpp

@@ -241,8 +241,12 @@ bool SplitterStep::mergePartialSolutions() const {
       // Finalize this solution.
       auto solution = CS.finalize();
       solutionMemory += solution.getTotalMemory();
-      if (CS.isDebugMode())
-        getDebugLogger() << "(composed solution " << CS.CurrentScore << ")\n";
+      if (CS.isDebugMode()) {
+        auto &log = getDebugLogger();
+        log << "(composed solution:";
+        CS.CurrentScore.print(log);
+        log << ")\n";
+      }
 
       // Save this solution.
       Solutions.push_back(std::move(solution));
@@ -429,8 +433,12 @@ StepResult ComponentStep::take(bool prevFailed) {
   }
 
   auto solution = CS.finalize();
-  if (CS.isDebugMode())
-    getDebugLogger() << "(found solution " << getCurrentScore() << ")\n";
+  if (CS.isDebugMode()) {
+    auto &log = getDebugLogger();
+    log << "(found solution:";
+    getCurrentScore().print(log);
+    log << ")\n";
+  }
 
   Solutions.push_back(std::move(solution));
   return finalize(/*isSuccess=*/true);

lib/Sema/ConstraintSystem.cpp

@@ -4624,7 +4624,7 @@ bool ConstraintSystem::diagnoseAmbiguityWithFixes(
         << " solutions with fixes ---\n";
     int i = 0;
     for (auto &solution : solutions) {
-      log << "--- Solution #" << i++ << "---\n";
+      log << "\n--- Solution #" << i++ << "---\n";
       solution.dump(log);
       log << "\n";
     }