[TypeCheckEffects] Downgrade new effects checker errors on if/switch expressions

to warnings until Swift 6.

Author: hborla

lib/Sema/TypeCheckEffects.cpp

@@ -2220,9 +2220,10 @@ class Context {
   }
 
   void diagnoseUncoveredThrowSite(ASTContext &ctx, ASTNode E,
-                                  const PotentialEffectReason &reason) {
+                                  const Classification &classification) {
     auto &Diags = ctx.Diags;
     auto message = diag::throwing_call_without_try;
+    const auto &reason = classification.getThrowReason();
     auto reasonKind = reason.getKind();
 
     bool suggestTryFixIt = reasonKind == PotentialEffectReason::Kind::Apply;
@@ -2262,7 +2263,8 @@ class Context {
       }
     }
 
-    Diags.diagnose(loc, message).highlight(highlight);
+    Diags.diagnose(loc, message).highlight(highlight)
+      .warnUntilSwiftVersionIf(classification.shouldDowngradeToWarning(), 6);
     maybeAddRethrowsNote(Diags, loc, reason);
 
     // If this is a call without expected 'try[?|!]', like this:
@@ -2565,6 +2567,12 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
 
       /// Are we in an 'async let' initializer context?
       InAsyncLet = 0x100,
+
+      /// Does an enclosing 'if' or 'switch' expr have a 'try'?
+      StmtExprCoversTry = 0x200,
+
+      /// Does an enclosing 'if' or 'switch' expr have an 'await'?
+      StmtExprCoversAwait = 0x400,
     };
   private:
     unsigned Bits;
@@ -2732,6 +2740,9 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
       Self.Flags.reset();
       Self.MaxThrowingKind = ConditionalEffectKind::None;
 
+      Self.Flags.mergeFrom(ContextFlags::StmtExprCoversTry, OldFlags);
+      Self.Flags.mergeFrom(ContextFlags::StmtExprCoversAwait, OldFlags);
+
       // Suppress 'try' coverage checking within a single level of
       // do/catch in debugger functions.
       if (OldFlags.has(ContextFlags::IsTopLevelDebuggerFunction))
@@ -2752,6 +2763,12 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
     void setCoverageForSingleValueStmtExpr() {
       resetCoverage();
       Self.Flags.mergeFrom(ContextFlags::InAsyncLet, OldFlags);
+
+      if (OldFlags.has(ContextFlags::IsTryCovered))
+        Self.Flags.set(ContextFlags::StmtExprCoversTry);
+
+      if (OldFlags.has(ContextFlags::IsAsyncCovered))
+        Self.Flags.set(ContextFlags::StmtExprCoversAwait);
     }
 
     void preserveCoverageFromSingleValueStmtExpr() {
@@ -3152,7 +3169,7 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
 
   ThrownErrorDestination
   checkThrowAsyncSite(ASTNode E, bool requiresTry,
-                      const Classification &classification) {
+                      Classification &classification) {
     // Suppress all diagnostics when there's an un-analyzable throw/async site.
     if (classification.isInvalid()) {
       Flags.set(ContextFlags::HasAnyThrowSite);
@@ -3185,6 +3202,8 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         Expr *expr = E.dyn_cast<Expr*>();
         Expr *anchor = walkToAnchor(expr, parentMap,
                                     CurContext.isWithinInterpolatedString());
+        if (Flags.has(ContextFlags::StmtExprCoversAwait))
+          classification.setDowngradeToWarning(true);
         if (uncoveredAsync.find(anchor) == uncoveredAsync.end())
           errorOrder.push_back(anchor);
         uncoveredAsync[anchor].emplace_back(
@@ -3223,8 +3242,10 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         CurContext.diagnoseUnhandledThrowSite(Ctx.Diags, E, isTryCovered,
                                               classification.getThrowReason());
       } else if (!isTryCovered) {
+        if (Flags.has(ContextFlags::StmtExprCoversTry))
+          classification.setDowngradeToWarning(true);
         CurContext.diagnoseUncoveredThrowSite(Ctx, E, // we want this one to trigger
-                                              classification.getThrowReason());
+                                              classification);
       } else {
         return checkThrownErrorType(
             E.getStartLoc(), classification.getThrownError());

test/expr/unary/do_expr.swift

@@ -155,7 +155,7 @@ func tryDo4() throws -> Int {
 func tryDo5() throws -> Int {
   return try do { tryDo4() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
-  // expected-error@-2 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-2 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-3 {{did you mean to use 'try'?}}
   // expected-note@-4 {{did you mean to handle error as optional value?}}
   // expected-note@-5 {{did you mean to disable error propagation?}}
@@ -164,7 +164,7 @@ func tryDo5() throws -> Int {
 func tryDo6() throws -> Int {
   try do { tryDo4() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
-  // expected-error@-2 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-2 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-3 {{did you mean to use 'try'?}}
   // expected-note@-4 {{did you mean to handle error as optional value?}}
   // expected-note@-5 {{did you mean to disable error propagation?}}
@@ -173,7 +173,7 @@ func tryDo6() throws -> Int {
 func tryDo7() throws -> Int {
   let x = try do { tryDo4() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
-  // expected-error@-2 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-2 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-3 {{did you mean to use 'try'?}}
   // expected-note@-4 {{did you mean to handle error as optional value?}}
   // expected-note@-5 {{did you mean to disable error propagation?}}
@@ -199,7 +199,7 @@ func tryDo10() throws -> Int {
 func tryDo11() throws -> Int {
   let x = try do { try tryDo4() } catch { tryDo4() }
   // expected-warning@-1 {{'try' has no effect on 'do-catch' expression}}
-  // expected-error@-2 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-2 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-3 {{did you mean to use 'try'?}}
   // expected-note@-4 {{did you mean to handle error as optional value?}}
   // expected-note@-5 {{did you mean to disable error propagation?}}
@@ -209,7 +209,7 @@ func tryDo11() throws -> Int {
 func tryDo12() throws -> Int {
   let x = try do { tryDo4() } catch { tryDo4() }
   // expected-warning@-1 {{'try' has no effect on 'do-catch' expression}}
-  // expected-error@-2 2{{call can throw but is not marked with 'try'}}
+  // expected-warning@-2 2{{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-3 2{{did you mean to use 'try'?}}
   // expected-note@-4 2{{did you mean to handle error as optional value?}}
   // expected-note@-5 2{{did you mean to disable error propagation?}}
@@ -219,13 +219,13 @@ func tryDo12() throws -> Int {
 func tryDo13() throws -> Int {
   let x = try do { // expected-warning {{'try' has no effect on 'do-catch' expression}}
     tryDo4() // expected-warning {{result of call to 'tryDo4()' is unused}}
-    // expected-error@-1 {{call can throw but is not marked with 'try'}}
+    // expected-warning@-1 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
     // expected-note@-2 {{did you mean to use 'try'?}}
     // expected-note@-3 {{did you mean to handle error as optional value?}}
     // expected-note@-4 {{did you mean to disable error propagation?}}
 
     _ = tryDo4()
-    // expected-error@-1 {{call can throw but is not marked with 'try'}}
+    // expected-warning@-1 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
     // expected-note@-2 {{did you mean to use 'try'?}}
     // expected-note@-3 {{did you mean to handle error as optional value?}}
     // expected-note@-4 {{did you mean to disable error propagation?}}
@@ -409,21 +409,21 @@ func awaitDo4() async -> Int {
 func awaitDo5() async -> Int {
   return await do { awaitDo4() }
   // expected-warning@-1 {{'await' has no effect on 'do' expression}}
-  // expected-error@-2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-2 {{expression is 'async' but is not marked with 'await'}}
   // expected-note@-3 {{call is 'async'}}
 }
 
 func awaitDo6() async -> Int {
   await do { awaitDo4() }
   // expected-warning@-1 {{'await' has no effect on 'do' expression}}
-  // expected-error@-2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-2 {{expression is 'async' but is not marked with 'await'}}
   // expected-note@-3 {{call is 'async'}}
 }
 
 func awaitDo7() async -> Int {
   let x = await do { awaitDo4() }
   // expected-warning@-1 {{'await' has no effect on 'do' expression}}
-  // expected-error@-2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-2 {{expression is 'async' but is not marked with 'await'}}
   // expected-note@-3 {{call is 'async'}}
   return x
 }
@@ -447,27 +447,27 @@ func awaitDo10() async -> Int {
 func awaitDo11() async -> Int {
   let x = await do { try await tryAwaitDo1() } catch { awaitDo4() }
   // expected-warning@-1 {{'await' has no effect on 'do-catch' expression}}
-  // expected-error@-2 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-2 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-3 {{call is 'async'}}
   return x
 }
 
 func awaitDo12() async -> Int {
   let x = await do { try tryAwaitDo1() } catch { awaitDo4() }
   // expected-warning@-1 {{'await' has no effect on 'do-catch' expression}}
-  // expected-error@-2 2{{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-2 2{{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-3 2{{call is 'async'}}
   return x
 }
 
 func awaitDo13() async throws -> Int {
   let x = await do { // expected-warning {{'await' has no effect on 'do-catch' expression}}
     awaitDo4() // expected-warning {{result of call to 'awaitDo4()' is unused}}
-    // expected-error@-1 {{expression is 'async' but is not marked with 'await'}}
+    // expected-warning@-1 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
     // expected-note@-2 {{call is 'async'}}
 
     _ = awaitDo4()
-    // expected-error@-1 {{expression is 'async' but is not marked with 'await'}}
+    // expected-warning@-1 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
     // expected-note@-2 {{call is 'async'}}
 
     _ = await awaitDo4() // Okay.
@@ -543,27 +543,27 @@ func tryAwaitDo3() async throws -> Int {
   try await do { tryAwaitDo2() } as Int
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-3 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-4 {{did you mean to use 'try'?}}
   // expected-note@-5 {{did you mean to handle error as optional value?}}
   // expected-note@-6 {{did you mean to disable error propagation?}}
-  // expected-error@-7 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-7 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-8 {{call is 'async'}}
 }
 
 func tryAwaitDo4() async throws -> Int {
   try await do { try tryAwaitDo2() } as Int
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-3 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-4 {{call is 'async'}}
 }
 
 func tryAwaitDo5() async throws -> Int {
   try await do { await tryAwaitDo2() } as Int
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-3 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-4 {{did you mean to use 'try'?}}
   // expected-note@-5 {{did you mean to handle error as optional value?}}
   // expected-note@-6 {{did you mean to disable error propagation?}}
@@ -579,27 +579,27 @@ func tryAwaitDo7() async throws -> Int {
   try await do { tryAwaitDo2() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-3 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-4 {{did you mean to use 'try'?}}
   // expected-note@-5 {{did you mean to handle error as optional value?}}
   // expected-note@-6 {{did you mean to disable error propagation?}}
-  // expected-error@-7 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-7 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-8 {{call is 'async'}}
 }
 
 func tryAwaitDo8() async throws -> Int {
   try await do { try tryAwaitDo2() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{expression is 'async' but is not marked with 'await'}}
+  // expected-warning@-3 {{expression is 'async' but is not marked with 'await'; this is an error in Swift 6}}
   // expected-note@-4 {{call is 'async'}}
 }
 
 func tryAwaitDo9() async throws -> Int {
   try await do { await tryAwaitDo2() }
   // expected-warning@-1 {{'try' has no effect on 'do' expression}}
   // expected-warning@-2 {{'await' has no effect on 'do' expression}}
-  // expected-error@-3 {{call can throw but is not marked with 'try'}}
+  // expected-warning@-3 {{call can throw but is not marked with 'try'; this is an error in Swift 6}}
   // expected-note@-4 {{did you mean to use 'try'?}}
   // expected-note@-5 {{did you mean to handle error as optional value?}}
   // expected-note@-6 {{did you mean to disable error propagation?}}