Check default arguments even if a function has no body (#18864)

This is needed for textual interfaces, but the behavior doesn't
have to be specific to that, since functions without bodies don't
come up in other situations.

Author: jrose-apple

lib/Sema/TypeCheckDecl.cpp

@@ -3123,12 +3123,12 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       }
     }
 
-    if (FD->hasBody()) {
-      // Record the body.
-      TC.definedFunctions.push_back(FD);
-    } else if (requiresDefinition(FD)) {
+    if (requiresDefinition(FD) && !FD->hasBody()) {
       // Complain if we should have a body.
       TC.diagnose(FD->getLoc(), diag::func_decl_without_brace);
+    } else {
+      // Record the body.
+      TC.definedFunctions.push_back(FD);
     }
   }
 
@@ -3354,20 +3354,18 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     AccessControlChecker::checkAccessControl(TC, CD);
     UsableFromInlineChecker::checkUsableFromInline(TC, CD);
 
-    if (CD->hasBody() && !CD->isMemberwiseInitializer()) {
-      TC.definedFunctions.push_back(CD);
-    } else if (requiresDefinition(CD)) {
+    if (requiresDefinition(CD) && !CD->hasBody()) {
       // Complain if we should have a body.
       TC.diagnose(CD->getLoc(), diag::missing_initializer_def);
+    } else {
+      TC.definedFunctions.push_back(CD);
     }
   }
 
   void visitDestructorDecl(DestructorDecl *DD) {
     TC.validateDecl(DD);
     TC.checkDeclAttributes(DD);
-
-    if (DD->hasBody())
-      TC.definedFunctions.push_back(DD);
+    TC.definedFunctions.push_back(DD);
   }
 };
 } // end anonymous namespace

lib/Sema/TypeCheckStmt.cpp

@@ -1537,6 +1537,7 @@ void TypeChecker::checkDefaultArguments(ParameterList *params,
 bool TypeChecker::typeCheckAbstractFunctionBodyUntil(AbstractFunctionDecl *AFD,
                                                      SourceLoc EndTypeCheckLoc) {
   validateDecl(AFD);
+  checkDefaultArguments(AFD->getParameters(), AFD);
 
   if (!AFD->getBody())
     return false;
@@ -1558,9 +1559,6 @@ bool TypeChecker::typeCheckAbstractFunctionBody(AbstractFunctionDecl *AFD) {
   if (AFD->isBodyTypeChecked())
     return false;
 
-  if (!AFD->getBody())
-    return false;
-
   FrontendStatsTracer StatsTracer(Context.Stats, "typecheck-fn", AFD);
   PrettyStackTraceDecl StackEntry("type-checking", AFD);
 
@@ -1579,17 +1577,16 @@ bool TypeChecker::typeCheckAbstractFunctionBody(AbstractFunctionDecl *AFD) {
   if (error)
     return true;
 
-  performAbstractFuncDeclDiagnostics(*this, AFD);
+  if (AFD->getBody())
+    performAbstractFuncDeclDiagnostics(*this, AFD);
+
   return false;
 }
 
 // Type check a function body (defined with the func keyword) that is either a
 // named function or an anonymous func expression.
 bool TypeChecker::typeCheckFunctionBodyUntil(FuncDecl *FD,
                                              SourceLoc EndTypeCheckLoc) {
-  // Check the default argument definitions.
-  checkDefaultArguments(FD->getParameters(), FD);
-
   // Clang imported inline functions do not have a Swift body to
   // typecheck.
   if (FD->getClangDecl())
@@ -1692,12 +1689,8 @@ static bool isKnownEndOfConstructor(ASTNode N) {
 
 bool TypeChecker::typeCheckConstructorBodyUntil(ConstructorDecl *ctor,
                                                 SourceLoc EndTypeCheckLoc) {
-  // Check the default argument definitions.
-  checkDefaultArguments(ctor->getParameters(), ctor);
-
   BraceStmt *body = ctor->getBody();
-  if (!body)
-    return true;
+  assert(body);
 
   // For constructors, we make sure that the body ends with a "return" stmt,
   // which we either implicitly synthesize, or the user can write.  This
@@ -1826,8 +1819,7 @@ bool TypeChecker::typeCheckDestructorBodyUntil(DestructorDecl *DD,
   StmtChecker SC(*this, static_cast<AbstractFunctionDecl *>(DD));
   SC.EndTypeCheckLoc = EndTypeCheckLoc;
   BraceStmt *Body = DD->getBody();
-  if (!Body)
-    return false;
+  assert(Body);
 
   bool HadError = SC.typeCheckBody(Body);
 

test/ModuleInterface/DefaultArgs.swiftinterface

@@ -0,0 +1,22 @@
+// RUN: %target-swift-frontend -emit-silgen %s | %FileCheck %s
+
+class SomeClass {
+  // Has defaults, but no body.
+  public func hasDefaults(a: Int = 4, b: Int = 1 + 2)
+
+  // CHECK-LABEL: sil hidden @$S11DefaultArgs9SomeClassC11hasDefaults1a1bySi_SitFfA_
+  // CHECK: integer_literal $Builtin.Int2048, 4
+  // CHECK: end sil function '$S11DefaultArgs9SomeClassC11hasDefaults1a1bySi_SitFfA_'
+
+  // CHECK-LABEL: sil hidden @$S11DefaultArgs9SomeClassC11hasDefaults1a1bySi_SitFfA0_
+  // CHECK: integer_literal $Builtin.Int2048, 1
+  // CHECK: integer_literal $Builtin.Int2048, 2
+  // CHECK: function_ref @$SSi1poiyS2i_SitFZ
+  // CHECK: end sil function '$S11DefaultArgs9SomeClassC11hasDefaults1a1bySi_SitFfA0_'
+
+  public init(a: Int = 5)
+
+  // CHECK-LABEL: sil hidden @$S11DefaultArgs9SomeClassC1aACSi_tcfcfA_
+  // CHECK: integer_literal $Builtin.Int2048, 5
+  // CHECK: end sil function '$S11DefaultArgs9SomeClassC1aACSi_tcfcfA_'
+}