[Clang] Fix -ast-dump-decl-types crashes on concepts (#108142)

Resolve #94928

This PR adds `if (TD->getTemplateDecl())` to prevent `InnerD` becoming
`nullptr`, suggested by @firstmoonlight.

I also add `-ast-dump-decl-types` option and declare type `CHECK` to the
testcase `clang/test/AST/ast-dump-concepts.cpp`.

---------

Co-authored-by: Aaron Ballman <aaron@aaronballman.com>

clang/docs/ReleaseNotes.rst

@@ -427,6 +427,8 @@ Miscellaneous Clang Crashes Fixed
 - Fixed a crash when function has more than 65536 parameters.
   Now a diagnostic is emitted. (#GH35741)
 
+- Fixed ``-ast-dump`` crashes on codes involving ``concept`` with ``-ast-dump-decl-types``. (#GH94928)
+
 OpenACC Specific Changes
 ------------------------
 

clang/lib/Frontend/ASTConsumers.cpp

@@ -101,7 +101,8 @@ namespace {
       if (DumpDeclTypes) {
         Decl *InnerD = D;
         if (auto *TD = dyn_cast<TemplateDecl>(D))
-          InnerD = TD->getTemplatedDecl();
+          if (Decl *TempD = TD->getTemplatedDecl())
+            InnerD = TempD;
 
         // FIXME: Support OutputFormat in type dumping.
         // FIXME: Support combining -ast-dump-decl-types with -ast-dump-lookups.

clang/test/AST/ast-dump-concepts.cpp

@@ -1,9 +1,9 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown -std=c++2a -ast-dump -ast-dump-filter Foo %s | FileCheck -strict-whitespace %s
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -std=c++2a -ast-dump -ast-dump-decl-types -ast-dump-filter Foo %s | FileCheck -strict-whitespace %s
 
 // Test with serialization:
 // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown -emit-pch -o %t %s
 // RUN: %clang_cc1 -x c++ -std=c++20 -triple x86_64-unknown-unknown -include-pch %t \
-// RUN: -ast-dump-all -ast-dump-filter Foo /dev/null \
+// RUN: -ast-dump-all -ast-dump-decl-types -ast-dump-filter Foo /dev/null \
 // RUN: | FileCheck --strict-whitespace %s
 
 template <typename T>
@@ -56,6 +56,9 @@ struct Foo {
   // CHECK: CXXFoldExpr {{.*}} <col:13, col:34>
   template <variadic_concept<int>... Ts>
   Foo();
+  
+  // CHECK:InjectedClassNameType
+  // CHECK-NEXT: CXXRecord {{.*}} 'Foo'
 };
 
 namespace GH82628 {
@@ -75,20 +78,28 @@ template <typename T>
 concept Foo = C<T>;
 
 // CHECK: TemplateTypeParmDecl {{.*}} Concept {{.*}} 'C' (UsingShadow {{.*}} 'C')
+// CHECK: QualType
+// CHECK-NEXT: `-BuiltinType {{.*}} 'bool'
 template <C T>
 constexpr bool FooVar = false;
 
 // CHECK: ConceptSpecializationExpr {{.*}} UsingShadow {{.*}} 'C'
+// CHECK: QualType
+// CHECK-NEXT: `-BuiltinType {{.*}} 'bool'
 template <typename T> requires C<T>
 constexpr bool FooVar2 = true;
 
 // CHECK: SimpleRequirement
 // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} UsingShadow {{.*}} 'C'
+// CHECK: QualType
+// CHECK-NEXT: `-BuiltinType {{.*}} 'bool'
 template <typename T> requires requires (T) { C<T>; }
 constexpr bool FooVar3 = true;
 
 // CHECK: NonTypeTemplateParmDecl
 // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} UsingShadow {{.*}} 'C'
+// CHECK: QualType
+// CHECK-NEXT: `-BuiltinType {{.*}} 'bool'
 template <C auto T>
 constexpr bool FooVar4 = bool(T());
 
@@ -97,7 +108,9 @@ constexpr bool FooVar4 = bool(T());
 // CHECK: NonTypeTemplateParmDecl {{.*}} depth 0 index 1 U
 // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} UsingShadow {{.*}} 'C'
 // CHECK: |-TemplateTypeParmDecl {{.*}} Concept {{.*}} 'C' (UsingShadow {{.*}} 'C') depth 0 index 2 V:auto
-
+// CHECK: FunctionProtoType
+// CHECK: `-Concept {{.*}} 'C'
+// CHECK: `-TemplateTypeParm {{.*}} 'V:auto'
 template <C... T, C auto U>
 auto FooFunc(C auto V) -> C decltype(auto) {
   // FIXME: TypeLocs inside of the function body cannot be dumped via -ast-dump for now.