[PATCH] D150955: [clang][AST] Propagate the value-dependent bit for VAArgExpr.

[Haojian Wu via Phabricator via cfe-commits]

hokein created this revision.
hokein added a reviewer: sammccall.
Herald added a project: All.
hokein requested review of this revision.
Herald added a project: clang.

Fixes https://github.com/llvm/llvm-project/issues/62711

We never set the value-dependent bit for the VAArgExpr before this
patch, this was fine becase the dependent-type TypoExpr was always
resolved before checking the operands (see https://github.com/llvm/llvm-project/blob/main/clang/lib/Sema/SemaExpr.cpp#L21173-L21180)

Now we have enabled the dependence by default for C, the typo expr is
not early resolved before checking rather than delayed (share the same
codepath with C++).

The fix is to propagate the value-dependent bit for VAArgExpr where it contains
a TypoExpr, so that the AST node can be handled properly.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D150955

Files:
  clang/lib/AST/ComputeDependence.cpp
  clang/test/AST/ast-dump-recovery.c


Index: clang/test/AST/ast-dump-recovery.c
===================================================================
--- clang/test/AST/ast-dump-recovery.c
+++ clang/test/AST/ast-dump-recovery.c
@@ -109,3 +109,11 @@
     b,
   };
 }
+
+// Verify no crash
+void test5_GH62711() {
+  // CHECK:      VAArgExpr {{.*}} 'int' contains-errors
+  // CHECK-NEXT: | `-ImplicitCastExpr {{.*}} '<dependent type>' contains-errors
+  // CHECK-NEXT: |   `-RecoveryExpr {{.*}} '<dependent type>' contains-errors
+  if (__builtin_va_arg(undef, int) << 1);
+}
Index: clang/lib/AST/ComputeDependence.cpp
===================================================================
--- clang/lib/AST/ComputeDependence.cpp
+++ clang/lib/AST/ComputeDependence.cpp
@@ -227,7 +227,7 @@
   auto D = toExprDependenceAsWritten(
                E->getWrittenTypeInfo()->getType()->getDependence()) |
            (E->getSubExpr()->getDependence() & ~ExprDependence::Type);
-  return D & ~ExprDependence::Value;
+  return D;
 }
 
 ExprDependence clang::computeDependence(NoInitExpr *E) {


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