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

to warnings until Swift 6.

(cherry picked from commit cc79dea)

Author: hborla

lib/Sema/TypeCheckEffects.cpp

@@ -1709,9 +1709,10 @@ 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;
@@ -1751,7 +1752,8 @@ 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:
@@ -2054,6 +2056,12 @@ 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;
@@ -2221,6 +2229,9 @@ 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))
@@ -2241,6 +2252,12 @@ 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() {
@@ -2556,11 +2573,11 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         effects.push_back(EffectKind::Async);
       }
 
+      auto classification = Classification::forEffect(effects,
+          ConditionalEffectKind::Always,
+          getKindOfEffectfulProp(member));
       bool requiresTry = getter->hasThrows();
-      checkThrowAsyncSite(E, requiresTry,
-                          Classification::forEffect(effects,
-                                  ConditionalEffectKind::Always,
-                                  getKindOfEffectfulProp(member)));
+      checkThrowAsyncSite(E, requiresTry, classification);
 
     } else {
       EffectList effects;
@@ -2600,10 +2617,10 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
         effects.push_back(EffectKind::Async);
       }
 
-      checkThrowAsyncSite(E, getter->hasThrows(),
-                          Classification::forEffect(effects,
-                                  ConditionalEffectKind::Always,
-                                  PotentialEffectReason::forPropertyAccess()));
+      auto classification = Classification::forEffect(effects,
+          ConditionalEffectKind::Always,
+          PotentialEffectReason::forPropertyAccess());
+      checkThrowAsyncSite(E, getter->hasThrows(), classification);
 
     } else if (E->isImplicitlyAsync()) {
       auto classification =  Classification::forUnconditional(
@@ -2713,7 +2730,7 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
   }
 
   void 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);
@@ -2746,6 +2763,8 @@ 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(
@@ -2784,8 +2803,10 @@ 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);
       }
       break;
     }

test/expr/unary/if_expr.swift

@@ -1010,7 +1010,7 @@ func tryIf4() throws -> Int {
 func tryIf5() throws -> Int {
   return try if .random() { tryIf4() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1019,7 +1019,7 @@ func tryIf5() throws -> Int {
 func tryIf6() throws -> Int {
   try if .random() { tryIf4() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1028,7 +1028,7 @@ func tryIf6() throws -> Int {
 func tryIf7() throws -> Int {
   let x = try if .random() { tryIf4() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1054,7 +1054,7 @@ func tryIf10() throws -> Int {
 func tryIf11() throws -> Int {
   let x = try if .random() { try tryIf4() } else { tryIf4() }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1064,7 +1064,7 @@ func tryIf11() throws -> Int {
 func tryIf12() throws -> Int {
   let x = try if .random() { tryIf4() } else { tryIf4() }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1074,13 +1074,13 @@ func tryIf12() throws -> Int {
 func tryIf13() throws -> Int {
   let x = try if .random() { // expected-warning {{'try' has no effect on 'if' expression}}
     tryIf4() // expected-warning {{result of call to 'tryIf4()' 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?}}
 
     _ = tryIf4()
-    // 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?}}
@@ -1105,7 +1105,7 @@ func throwsBool() throws -> Bool { true }
 func tryIf14() throws -> Int {
   try if throwsBool() { 0 } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' 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?}}
@@ -1245,21 +1245,21 @@ func awaitIf4() async -> Int {
 func awaitIf5() async -> Int {
   return await if .random() { awaitIf4() } else { 1 }
   // expected-warning@-1 {{'await' has no effect on 'if' 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'}}
 }
 
 func awaitIf6() async -> Int {
   await if .random() { awaitIf4() } else { 1 }
   // expected-warning@-1 {{'await' has no effect on 'if' 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'}}
 }
 
 func awaitIf7() async -> Int {
   let x = await if .random() { awaitIf4() } else { 1 }
   // expected-warning@-1 {{'await' has no effect on 'if' 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
 }
@@ -1283,27 +1283,27 @@ func awaitIf10() async -> Int {
 func awaitIf11() async -> Int {
   let x = await if .random() { await awaitIf4() } else { awaitIf4() }
   // expected-warning@-1 {{'await' has no effect on 'if' 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 awaitIf12() async -> Int {
   let x = await if .random() { awaitIf4() } else { awaitIf4() }
   // expected-warning@-1 {{'await' has no effect on 'if' 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 awaitIf13() async throws -> Int {
   let x = await if .random() { // expected-warning {{'await' has no effect on 'if' expression}}
     awaitIf4() // expected-warning {{result of call to 'awaitIf4()' 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'}}
 
     _ = awaitIf4()
-    // 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 awaitIf4() // Okay.
@@ -1326,7 +1326,7 @@ func asyncBool() async -> Bool { true }
 func awaitIf14() async -> Int {
   await if asyncBool() { 0 } else { 1 }
   // expected-warning@-1 {{'await' has no effect on 'if' 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'}}
 }
 
@@ -1378,27 +1378,27 @@ func tryAwaitIf3() async throws -> Int {
   try await if .random() { tryAwaitIf2() } else { 1 } as Int
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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 tryAwaitIf4() async throws -> Int {
   try await if .random() { try tryAwaitIf2() } else { 1 } as Int
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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 tryAwaitIf5() async throws -> Int {
   try await if .random() { await tryAwaitIf2() } else { 1 } as Int
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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?}}
@@ -1414,27 +1414,27 @@ func tryAwaitIf7() async throws -> Int {
   try await if .random() { tryAwaitIf2() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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 tryAwaitIf8() async throws -> Int {
   try await if .random() { try tryAwaitIf2() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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 tryAwaitIf9() async throws -> Int {
   try await if .random() { await tryAwaitIf2() } else { 1 }
   // expected-warning@-1 {{'try' has no effect on 'if' expression}}
   // expected-warning@-2 {{'await' has no effect on 'if' 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?}}