issue #65913 - Correct wrong insertion point suggestion when using shorthand optional binding by looking for implicitDeclRefExpr that is optional and points to a VarDecl. If we have that, get the name and insert with fixItInsertAfter instead of fixItInsert.

Author: James Brown

lib/Sema/TypeCheckEffects.cpp

@@ -3581,7 +3581,7 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
     Ctx.Diags.diagnose(E->getAwaitLoc(), diag::no_async_in_await);
   }
 
-  void diagnoseUncoveredAsyncSite(const Expr *anchor) const {
+  void diagnoseUncoveredAsyncSite(Expr *anchor) const {
     auto asyncPointIter = uncoveredAsync.find(anchor);
     if (asyncPointIter == uncoveredAsync.end())
       return;
@@ -3593,16 +3593,38 @@ class CheckEffectsCoverage : public EffectsHandlingWalker<CheckEffectsCoverage>
       if (const AnyTryExpr *tryExpr = dyn_cast<AnyTryExpr>(autoClosure->getSingleExpressionBody()))
         awaitInsertLoc = tryExpr->getSubExpr()->getStartLoc();
     }
+    
+    auto findShorthandOptionalBinding = [&](Expr *anchor) -> VarDecl * {
+      VarDecl *varDecl = nullptr;
+      if (!anchor->getType()->isOptional())
+        return nullptr;
+      anchor->forEachChildExpr([&](Expr *expr) -> Expr * {
+        if (isa<DeclRefExpr>(expr) && expr->isImplicit()) {
+          varDecl = dyn_cast<VarDecl>(expr->getReferencedDecl().getDecl());
+          return nullptr;
+        }
+        return expr;
+      });
+      return varDecl;
+    };
 
     bool downgradeToWarning = llvm::all_of(errors,
         [&](DiagnosticInfo diag) -> bool {
           return diag.downgradeToWarning;
         });
-
-    Ctx.Diags.diagnose(anchor->getStartLoc(), diag::async_expr_without_await)
-      .warnUntilSwiftVersionIf(downgradeToWarning, 6)
-      .fixItInsert(awaitInsertLoc, "await ")
-      .highlight(anchor->getSourceRange());
+    
+    if (auto *varDecl = findShorthandOptionalBinding(anchor)) {
+      Ctx.Diags.diagnose(anchor->getStartLoc(), diag::async_expr_without_await)
+        .warnUntilSwiftVersionIf(downgradeToWarning, 6)
+        .fixItInsertAfter(anchor->getStartLoc(),
+                          " = await " + varDecl->getNameStr().str())
+        .highlight(anchor->getSourceRange());
+    } else {
+      Ctx.Diags.diagnose(anchor->getStartLoc(), diag::async_expr_without_await)
+        .warnUntilSwiftVersionIf(downgradeToWarning, 6)
+        .fixItInsert(awaitInsertLoc, "await ")
+        .highlight(anchor->getSourceRange());
+    }
 
     for (const DiagnosticInfo &diag: errors) {
       switch (diag.reason.getKind()) {

test/Sema/diag_async_expr_without_await.swift

@@ -0,0 +1,44 @@
+// RUN: %target-typecheck-verify-swift -disable-availability-checking
+
+// REQUIRES: concurrency
+class A {}
+class B: A {}
+typealias Foo = (name: String, age: Int)
+func f(_ x: String) async -> String? { x }
+func test() async {
+  async let result: B? = nil
+  async let person: Foo? = nil
+  if let result: A = result {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{22-22=await }}
+  // expected-warning@-1 {{immutable value 'result' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'result' is 'async'}}
+  if let result: A {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{19-19= = await result}}
+  // expected-warning@-1 {{immutable value 'result' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'result' is 'async'}}
+  if let result = result {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{19-19=await }}
+  // expected-warning@-1 {{value 'result' was defined but never used; consider replacing with boolean test}}
+  // expected-note@-2 {{reference to async let 'result' is 'async'}}
+  if let result {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{16-16= = await result}}
+  // expected-warning@-1 {{value 'result' was defined but never used; consider replacing with boolean test}}
+  // expected-note@-2 {{reference to async let 'result' is 'async'}}
+  if let person: Foo = person {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{24-24=await }}
+  // expected-warning@-1 {{immutable value 'person' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  if let person: Foo {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{21-21= = await person}}
+  // expected-warning@-1 {{immutable value 'person' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  if let person: (String, Int) = person {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{34-34=await }}
+  // expected-warning@-1 {{immutable value 'person' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  if let person: (String, Int) {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{31-31= = await person}}
+  // expected-warning@-1 {{immutable value 'person' was never used; consider replacing with '_' or removing it}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  if let person = person {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{19-19=await }}
+  // expected-warning@-1 {{value 'person' was defined but never used; consider replacing with boolean test}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  if let person {} // expected-error {{expression is 'async' but is not marked with 'await'}} {{16-16= = await person}}
+  // expected-warning@-1 {{value 'person' was defined but never used; consider replacing with boolean test}}
+  // expected-note@-2 {{reference to async let 'person' is 'async'}}
+  let a = f("a") // expected-error {{expression is 'async' but is not marked with 'await'}} {{11-11=await }}
+  // expected-warning@-1 {{initialization of immutable value 'a' was never used; consider replacing with assignment to '_' or removing it}}
+  // expected-note@-2 {{call is 'async'}}
+}