[PATCH] D135362: [clang] Make variables of undeduced types to have dependent alignment

[Aleksandr Platonov via Phabricator via cfe-commits]

ArcsinX created this revision.
ArcsinX added reviewers: aaron.ballman, rsmith, mizvekov.
Herald added a project: All.
ArcsinX requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Without this patch `VarDecl::hasDependent()` checks only undeduced auto types, so can give false negatives result for other undeduced types.
This lead to crashes in sequence `!VarDecl::hasDepentent()` => `getDeclAlign()`.

It seems this problem appeared since D105380 <https://reviews.llvm.org/D105380>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D135362

Files:
  clang/lib/AST/Decl.cpp
  clang/test/Sema/tls_alignment.cpp


Index: clang/test/Sema/tls_alignment.cpp
===================================================================
--- clang/test/Sema/tls_alignment.cpp
+++ clang/test/Sema/tls_alignment.cpp
@@ -1,6 +1,6 @@
 // TLS variable cannot be aligned to more than 32 bytes on PS4.
 
-// RUN: %clang_cc1 -triple x86_64-scei-ps4 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-scei-ps4 -std=c++17 -fsyntax-only -verify %s
 
 
 // A non-aligned type.
@@ -18,6 +18,12 @@
     int some_aligned_data[12] __attribute__(( aligned(64) )); // 48 bytes of stuff, aligned to 64.
 };
 
+// A templated type
+template <typename>
+struct templated_struct {};
+// expected-note at -1{{candidate template ignored: couldn't infer template argument ''}}
+// expected-note at -2{{candidate function template not viable: requires 1 argument, but 0 were provided}}
+
 // A typedef of the aligned struct.
 typedef aligned_struct another_aligned_struct;
 
@@ -42,6 +48,9 @@
 // Variable aligned because of typedef, second case.
 __thread yet_another_aligned_struct        bar5; // expected-error{{alignment (64) of thread-local variable}}
 
+// No crash for undeduced type.
+__thread templated_struct                  bar6; // expected-error{{no viable constructor or deduction guide for deduction of template arguments of 'templated_struct'}}
+
 int baz ()
 {
     return foo.some_data[0] + bar.some_data[1] + bar2.some_data[2] +
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -2581,7 +2581,7 @@
 
 bool VarDecl::hasDependentAlignment() const {
   QualType T = getType();
-  return T->isDependentType() || T->isUndeducedAutoType() ||
+  return T->isDependentType() || T->isUndeducedType() ||
          llvm::any_of(specific_attrs<AlignedAttr>(), [](const AlignedAttr *AA) {
            return AA->isAlignmentDependent();
          });


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