[clang] [clang] Preserve the initializer when variable declaration deduction fails (PR #173546)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Haojian Wu (hokein)

<details>
<summary>Changes</summary>

Fix https://github.com/clangd/clangd/issues/2572.

---
Full diff: https://github.com/llvm/llvm-project/pull/173546.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaDecl.cpp (+8-1) 
- (modified) clang/test/AST/ast-dump-recovery.cpp (+8) 


``````````diff
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 1a5e8c607a242..2cbb7b9fd3e17 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -13839,8 +13839,15 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
       return;
     }
 
-    if (DeduceVariableDeclarationType(VDecl, DirectInit, Init))
+    if (DeduceVariableDeclarationType(VDecl, DirectInit, Init)) {
+      assert(VDecl->isInvalidDecl() &&
+             "decl should be invalidated when deduce fails");
+      if (auto *RecoveryExpr =
+              CreateRecoveryExpr(Init->getBeginLoc(), Init->getEndLoc(), {Init})
+                  .get())
+        VDecl->setInit(RecoveryExpr);
       return;
+    }
   }
 
   this->CheckAttributesOnDeducedType(RealDecl);
diff --git a/clang/test/AST/ast-dump-recovery.cpp b/clang/test/AST/ast-dump-recovery.cpp
index 060ae3b62b6f8..80ec0a449d556 100644
--- a/clang/test/AST/ast-dump-recovery.cpp
+++ b/clang/test/AST/ast-dump-recovery.cpp
@@ -301,3 +301,11 @@ void foo() {
   U g{};
 }
 } // namespace GH112560
+
+// CHECK:     VarDecl {{.*}} invalid x 'auto *' cinit
+// CHECK-NEXT: `-RecoveryExpr {{.*}} '<dependent type>' contains-errors lvalue
+// CHECK-NEXT:   `-CallExpr {{.*}} 'int'
+// DISABLED-NOT: -RecoveryExpr {{.*}} contains-errors
+void brokenDeducedVarDecl() {
+   auto* x = some_func(nullptr);
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/173546