Sema: Store an 'invalid' bit in PoundHasSymbolInfo to avoid repeated if #_hasSymbol diagnostics.

Author: tshortli

include/swift/AST/Stmt.h

@@ -398,14 +398,15 @@ class alignas(8) PoundAvailableInfo final :
 class PoundHasSymbolInfo final : public ASTAllocated<PoundHasSymbolInfo> {
   Expr *SymbolExpr;
   ConcreteDeclRef ReferencedDecl;
+  bool Invalid;
 
   SourceLoc PoundLoc;
   SourceLoc LParenLoc;
   SourceLoc RParenLoc;
 
   PoundHasSymbolInfo(SourceLoc PoundLoc, SourceLoc LParenLoc, Expr *SymbolExpr,
                      SourceLoc RParenLoc)
-      : SymbolExpr(SymbolExpr), ReferencedDecl(), PoundLoc(PoundLoc),
+      : SymbolExpr(SymbolExpr), ReferencedDecl(), Invalid(), PoundLoc(PoundLoc),
         LParenLoc(LParenLoc), RParenLoc(RParenLoc){};
 
 public:
@@ -419,6 +420,10 @@ class PoundHasSymbolInfo final : public ASTAllocated<PoundHasSymbolInfo> {
   ConcreteDeclRef getReferencedDecl() { return ReferencedDecl; }
   void setReferencedDecl(ConcreteDeclRef CDR) { ReferencedDecl = CDR; }
 
+  /// Returns true if the referenced decl has been diagnosed as invalid.
+  bool isInvalid() const { return Invalid; }
+  void setInvalid() { Invalid = true; }
+
   SourceLoc getLParenLoc() const { return LParenLoc; }
   SourceLoc getRParenLoc() const { return RParenLoc; }
   SourceLoc getStartLoc() const { return PoundLoc; }

lib/Sema/CSApply.cpp

@@ -8927,12 +8927,14 @@ ExprWalker::rewriteTarget(SolutionApplicationTarget target) {
 
       case StmtConditionElement::CK_HasSymbol: {
         ConstraintSystem &cs = solution.getConstraintSystem();
+        auto info = condElement.getHasSymbolInfo();
         auto target = *cs.getSolutionApplicationTarget(&condElement);
         auto resolvedTarget = rewriteTarget(target);
-        if (!resolvedTarget)
+        if (!resolvedTarget) {
+          info->setInvalid();
           return None;
+        }
 
-        auto info = condElement.getHasSymbolInfo();
         auto rewrittenExpr = resolvedTarget->getAsExpr();
         info->setSymbolExpr(rewrittenExpr);
         info->setReferencedDecl(

lib/Sema/MiscDiagnostics.cpp

@@ -4319,6 +4319,9 @@ static void checkLabeledStmtConditions(ASTContext &ctx,
 
     case StmtConditionElement::CK_HasSymbol: {
       auto info = elt.getHasSymbolInfo();
+      if (info->isInvalid())
+        break;
+
       auto symbolExpr = info->getSymbolExpr();
       if (!symbolExpr)
         break;
@@ -4334,11 +4337,13 @@ static void checkLabeledStmtConditions(ASTContext &ctx,
           ctx.Diags.diagnose(symbolExpr->getLoc(),
                              diag::has_symbol_decl_must_be_weak,
                              decl->getDescriptiveKind(), decl->getName());
+          info->setInvalid();
         }
       } else {
         // Diagnose because we weren't able to interpret the expression as one
         // that uniquely identifies a single declaration.
         ctx.Diags.diagnose(symbolExpr->getLoc(), diag::has_symbol_invalid_expr);
+        info->setInvalid();
       }
       break;
     }

lib/Sema/TypeCheckStmt.cpp

@@ -504,10 +504,13 @@ bool TypeChecker::typeCheckStmtConditionElement(StmtConditionElement &elt,
     auto exprTy = TypeChecker::typeCheckExpression(E, dc);
     Info->setSymbolExpr(E);
 
-    if (exprTy)
-      Info->setReferencedDecl(getReferencedDeclForHasSymbolCondition(E));
+    if (!exprTy) {
+      Info->setInvalid();
+      return true;
+    }
 
-    return !exprTy;
+    Info->setReferencedDecl(getReferencedDeclForHasSymbolCondition(E));
+    return false;
   }
 
   if (auto E = elt.getBooleanOrNull()) {

test/Sema/has_symbol.swift

@@ -1,6 +1,7 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module -emit-module-path %t/has_symbol_helper.swiftmodule -parse-as-library %S/Inputs/has_symbol_helper.swift -enable-library-evolution
 // RUN: %target-typecheck-verify-swift -disable-availability-checking -I %t
+// RUN: %target-typecheck-verify-swift -disable-availability-checking -I %t -enable-experimental-feature ResultBuilderASTTransform
 
 // UNSUPPORTED: OS=windows-msvc
 
@@ -161,4 +162,9 @@ struct MyView {
     if #_hasSymbol(localFunc) { image } // expected-warning {{global function 'localFunc()' is not a weakly linked declaration}}
     else { image }
   }
+
+  @ViewBuilder var noArgFuncView: some View {
+    if #_hasSymbol(noArgFunc()) { image } // expected-error {{#_hasSymbol condition must refer to a declaration}}
+    else { image }
+  }
 }