[Type Checker] Separate "override" checking into its own file

lib/Sema/CMakeLists.txt

@@ -39,6 +39,7 @@ add_swift_library(swiftSema STATIC
   TypeCheckCircularity.cpp
   TypeCheckConstraints.cpp
   TypeCheckDecl.cpp
+  TypeCheckDeclOverride.cpp
   TypeCheckError.cpp
   TypeCheckExpr.cpp
   TypeCheckExprObjC.cpp

lib/Sema/CSDiag.cpp

@@ -18,6 +18,7 @@
 #include "CSDiag.h"
 #include "CalleeCandidateInfo.h"
 #include "MiscDiagnostics.h"
+#include "TypeCheckAvailability.h"
 #include "TypoCorrection.h"
 #include "swift/AST/ASTWalker.h"
 #include "swift/AST/GenericEnvironment.h"
@@ -4404,7 +4405,7 @@ class ArgumentMatcher : public MatchCallArgumentListener {
     assert(!newNames.empty() && "No arguments were re-labeled");
 
     // Let's diagnose labeling problem but only related to corrected ones.
-    if (diagnoseArgumentLabelError(TC, ArgExpr, newNames, IsSubscript))
+    if (diagnoseArgumentLabelError(TC.Context, ArgExpr, newNames, IsSubscript))
       Diagnosed = true;
 
     return true;
@@ -6351,7 +6352,7 @@ bool FailureDiagnosis::visitCoerceExpr(CoerceExpr *CE) {
     // type-checking sub-expression as unavaible
     // declaration, let's try to diagnose that here.
     if (AvailableAttr::isUnavailable(decl))
-      return CS.TC.diagnoseExplicitUnavailability(
+      return diagnoseExplicitUnavailability(
           decl, expr->getSourceRange(), CS.DC, dyn_cast<ApplyExpr>(expr));
   }
 
@@ -7908,8 +7909,8 @@ bool FailureDiagnosis::diagnoseMemberFailures(
   if (allUnavailable) {
     auto firstDecl = viableCandidatesToReport[0].getDecl();
     // FIXME: We need the enclosing CallExpr to rewrite the argument labels.
-    if (CS.TC.diagnoseExplicitUnavailability(firstDecl, BaseLoc, CS.DC,
-                                             /*call*/ nullptr))
+    if (diagnoseExplicitUnavailability(firstDecl, BaseLoc, CS.DC,
+                                       /*call*/ nullptr))
       return true;
   }
 

lib/Sema/CalleeCandidateInfo.cpp

@@ -17,6 +17,7 @@
 #include "ConstraintSystem.h"
 #include "CSDiag.h"
 #include "CalleeCandidateInfo.h"
+#include "TypeCheckAvailability.h"
 #include "swift/AST/GenericEnvironment.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/TypeWalker.h"
@@ -1057,8 +1058,8 @@ bool CalleeCandidateInfo::diagnoseSimpleErrors(const Expr *E) {
   if (closeness == CC_Unavailable) {
     auto decl = candidates[0].getDecl();
     assert(decl && "Only decl-based candidates may be marked unavailable");
-    return CS.TC.diagnoseExplicitUnavailability(decl, loc, CS.DC,
-                                                dyn_cast<CallExpr>(E));
+    return diagnoseExplicitUnavailability(decl, loc, CS.DC,
+                                          dyn_cast<CallExpr>(E));
   }
 
   // Handle symbols that are matches, but are not accessible from the current

lib/Sema/CodeSynthesis.h

@@ -98,6 +98,8 @@ void makeDynamic(ASTContext &ctx, ValueDecl *D);
 void markAsObjC(TypeChecker &TC, ValueDecl *D,
                 Optional<ObjCReason> isObjC,
                 Optional<ForeignErrorConvention> errorConvention = None);
+
+// Implemented in TypeCheckerOverride.cpp
 bool checkOverrides(TypeChecker &TC, ValueDecl *decl);
 
 // These are implemented in CodeSynthesis.cpp.

lib/Sema/MiscDiagnostics.cpp

@@ -1837,7 +1837,8 @@ bool TypeChecker::getDefaultGenericArgumentsString(
 
 /// Diagnose an argument labeling issue, returning true if we successfully
 /// diagnosed the issue.
-bool swift::diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
+bool swift::diagnoseArgumentLabelError(ASTContext &ctx,
+                                       const Expr *expr,
                                        ArrayRef<Identifier> newNames,
                                        bool isSubscript,
                                        InFlightDiagnostic *existingDiag) {
@@ -1848,6 +1849,7 @@ bool swift::diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
     return *diagOpt;
   };
 
+  auto &diags = ctx.Diags;
   auto tuple = dyn_cast<TupleExpr>(expr);
   if (!tuple) {
     llvm::SmallString<16> str;
@@ -1868,9 +1870,10 @@ bool swift::diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
             str = ".";
             str += field.getName().str();
             if (!existingDiag) {
-              diagOpt.emplace(TC.diagnose(expr->getStartLoc(),
-                                          diag::extra_named_single_element_tuple,
-                                          field.getName().str()));
+              diagOpt.emplace(
+                          diags.diagnose(expr->getStartLoc(),
+                                         diag::extra_named_single_element_tuple,
+                                         field.getName().str()));
             }
             getDiag().fixItInsertAfter(expr->getEndLoc(), str);
             return true;
@@ -1894,9 +1897,10 @@ bool swift::diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
     str += newNames[0].str();
     str += ": ";
     if (!existingDiag) {
-      diagOpt.emplace(TC.diagnose(expr->getStartLoc(),
-                                  diag::missing_argument_labels,
-                                  false, str.str().drop_back(), isSubscript));
+      diagOpt.emplace(diags.diagnose(expr->getStartLoc(),
+                                     diag::missing_argument_labels,
+                                     false, str.str().drop_back(),
+                                     isSubscript));
     }
     getDiag().fixItInsert(expr->getStartLoc(), str);
     return true;
@@ -1962,17 +1966,21 @@ bool swift::diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
 
       StringRef haveStr = haveBuffer;
       StringRef expectedStr = expectedBuffer;
-      diagOpt.emplace(TC.diagnose(expr->getLoc(), diag::wrong_argument_labels,
-                                  plural, haveStr, expectedStr, isSubscript));
+      diagOpt.emplace(diags.diagnose(expr->getLoc(),
+                                     diag::wrong_argument_labels,
+                                     plural, haveStr, expectedStr,
+                                     isSubscript));
     } else if (numMissing > 0) {
       StringRef missingStr = missingBuffer;
-      diagOpt.emplace(TC.diagnose(expr->getLoc(), diag::missing_argument_labels,
-                                  plural, missingStr, isSubscript));
+      diagOpt.emplace(diags.diagnose(expr->getLoc(),
+                                     diag::missing_argument_labels,
+                                     plural, missingStr, isSubscript));
     } else {
       assert(numExtra > 0);
       StringRef extraStr = extraBuffer;
-      diagOpt.emplace(TC.diagnose(expr->getLoc(), diag::extra_argument_labels,
-                                  plural, extraStr, isSubscript));
+      diagOpt.emplace(diags.diagnose(expr->getLoc(),
+                                     diag::extra_argument_labels,
+                                     plural, extraStr, isSubscript));
     }
   }
 

lib/Sema/MiscDiagnostics.h

@@ -61,7 +61,8 @@ void fixItAccess(InFlightDiagnostic &diag, ValueDecl *VD,
 /// error diagnostic.
 ///
 /// \returns true if the issue was diagnosed
-bool diagnoseArgumentLabelError(TypeChecker &TC, const Expr *expr,
+bool diagnoseArgumentLabelError(ASTContext &ctx,
+                                const Expr *expr,
                                 ArrayRef<Identifier> newNames,
                                 bool isSubscript,
                                 InFlightDiagnostic *existingDiag = nullptr);