From 986cbd80d1dc838c61abff24b8d7ac28dcf4ac2a Mon Sep 17 00:00:00 2001
From: Takuya Shimizu <shimizu2486@gmail.com>
Date: Tue, 23 May 2023 00:29:20 +0900
Subject: [PATCH] [clang][AST] TextNodeDumper should not evaluate the
 initializer of constexpr variable declaration when it has a dependent type

`TextNodeDumper` enabed through `-ast-dump` flag should not evlauate the initializer when it visits a constexpr `VarDecl` node if it has a dependent type.

I found a crashing case fixed by this change and added it as a test case.
`template <typename T> constexpr T call_init(0);`
Link: https://godbolt.org/z/3bG9Pjj5E

This is a fix for the regression caused by D146358

Differential Revision: https://reviews.llvm.org/D151033
---
 clang/docs/ReleaseNotes.rst      |  2 ++
 clang/lib/AST/TextNodeDumper.cpp |  3 ++-
 clang/test/AST/ast-dump-decl.cpp | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c80cc89..a55e969 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -420,6 +420,8 @@ Bug Fixes in This Version
   (`#62711 <https://github.com/llvm/llvm-project/issues/62711>`_).
 - Fix crash on attempt to initialize union with flexible array member.
   (`#61746 <https://github.com/llvm/llvm-project/issues/61746>`_).
+- Clang `TextNodeDumper` enabled through `-ast-dump` flag no longer evaluates the
+  initializer of constexpr `VarDecl` if the declaration has a dependent type.
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index 3817025..b89a13d 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -1821,7 +1821,8 @@ void TextNodeDumper::VisitVarDecl(const VarDecl *D) {
   if (D->hasInit()) {
     const Expr *E = D->getInit();
     // Only dump the value of constexpr VarDecls for now.
-    if (E && !E->isValueDependent() && D->isConstexpr()) {
+    if (E && !E->isValueDependent() && D->isConstexpr() &&
+        !D->getType()->isDependentType()) {
       const APValue *Value = D->evaluateValue();
       if (Value)
         AddChild("value", [=] { Visit(*Value, E->getType()); });
diff --git a/clang/test/AST/ast-dump-decl.cpp b/clang/test/AST/ast-dump-decl.cpp
index 3be99c9..276a209 100644
--- a/clang/test/AST/ast-dump-decl.cpp
+++ b/clang/test/AST/ast-dump-decl.cpp
@@ -818,3 +818,38 @@ namespace Comment {
 // CHECK:       `-TextComment
 // CHECK: VarDecl {{.*}} Test 'int' extern
 // CHECK-NOT: FullComment
+
+namespace TestConstexprVariableTemplateWithInitializer {
+  template<typename T> constexpr T foo{};
+  // CHECK:      VarTemplateDecl 0x{{.+}} <{{.+}}:[[@LINE-1]]:3, col:40> col:36 foo
+  // CHECK-NEXT: |-TemplateTypeParmDecl 0x{{.+}} <col:12, col:21> col:21 referenced typename depth 0 index 0 T
+  // CHECK-NEXT: `-VarDecl 0x{{.+}} <col:24, col:40> col:36 foo 'const T' constexpr listinit
+  // CHECK-NEXT:  `-InitListExpr 0x{{.+}} <col:39, col:40> 'void'
+
+  template<typename T> constexpr int val{42};
+  // CHECK:      VarTemplateDecl 0x{{.+}} <{{.+}}:[[@LINE-1]]:3, col:44> col:38 val
+  // CHECK-NEXT: |-TemplateTypeParmDecl 0x{{.+}} <col:12, col:21> col:21 typename depth 0 index 0 T
+  // CHECK-NEXT: `-VarDecl 0x{{.+}} <col:24, col:44> col:38 val 'const int' constexpr listinit
+  // CHECK-NEXT:  |-value: Int 42
+  // CHECK-NEXT:  `-InitListExpr 0x{{.+}} <col:41, col:44> 'int'
+
+  template <typename _Tp>
+  struct in_place_type_t {
+    explicit in_place_type_t() = default;
+  };
+
+  template <typename _Tp>
+  inline constexpr in_place_type_t<_Tp> in_place_type{};
+  // CHECK:     -VarTemplateDecl 0x{{.+}} <line:[[@LINE-2]]:3, line:[[@LINE-1]]:55> col:41 in_place_type
+  // CHECK-NEXT: |-TemplateTypeParmDecl 0x{{.+}} <line:[[@LINE-3]]:13, col:22> col:22 referenced typename depth 0 index 0 _Tp
+  // CHECK-NEXT: `-VarDecl 0x{{.+}} <line:[[@LINE-3]]:3, col:55> col:41 in_place_type 'const in_place_type_t<_Tp>':'const in_place_type_t<_Tp>' inline constexpr listinit
+  // CHECK-NEXT:  `-InitListExpr 0x{{.+}} <col:54, col:55> 'void'
+
+  template <typename T> constexpr T call_init(0);
+  // CHECK:     -VarTemplateDecl 0x{{.+}} <line:[[@LINE-1]]:3, col:48> col:37 call_init
+  // CHECK-NEXT: |-TemplateTypeParmDecl 0x{{.+}} <col:13, col:22> col:22 referenced typename depth 0 index 0 T
+  // CHECK-NEXT: `-VarDecl 0x{{.+}} <col:25, col:48> col:37 call_init 'const T' constexpr callinit
+  // CHECK-NEXT:  `-ParenListExpr 0x{{.+}} <col:46, col:48> 'NULL TYPE'
+  // CHECK-NEXT:   `-IntegerLiteral 0x{{.+}} <col:47> 'int' 0
+
+}
-- 
2.7.4