[clang] Add dump() support for lvalue APValues

Add some lvalue information to the `dump()` output of lvalue APValues.

Author: tbaederr

clang/lib/AST/TextNodeDumper.cpp

@@ -710,10 +710,39 @@ void TextNodeDumper::Visit(const APValue &Value, QualType Ty) {
          << GetApproxValue(Value.getComplexFloatImag()) << 'i';
     }
     return;
-  case APValue::LValue:
+  case APValue::LValue: {
     (void)Context;
-    OS << "LValue <todo>";
+    OS << "LValue Base=";
+    APValue::LValueBase B = Value.getLValueBase();
+    if (B.isNull())
+      OS << "null";
+    else if (const auto *BE = B.dyn_cast<const Expr *>()) {
+      OS << BE->getStmtClassName() << ' ';
+      dumpPointer(BE);
+    } else {
+      const auto *VDB = B.get<const ValueDecl *>();
+      OS << VDB->getDeclKindName() << "Decl";
+      dumpPointer(VDB);
+    }
+    OS << ", Null=" << Value.isNullPointer()
+       << ", Offset=" << Value.getLValueOffset().getQuantity()
+       << ", HasPath=" << Value.hasLValuePath();
+    if (Value.hasLValuePath()) {
+      OS << ", PathLength=" << Value.getLValuePath().size();
+      OS << ", Path=(";
+      bool First = true;
+      for (const auto &PathEntry : Value.getLValuePath()) {
+        // We're printing all entries as array indices because don't have the
+        // type information here to do anything else.
+        OS << PathEntry.getAsArrayIndex();
+        if (First && Value.getLValuePath().size() > 1)
+          OS << ", ";
+        First = false;
+      }
+      OS << ")";
+    }
     return;
+  }
   case APValue::Array: {
     unsigned ArraySize = Value.getArraySize();
     unsigned NumInitializedElements = Value.getArrayInitializedElts();

clang/test/AST/ast-dump-APValue-lvalue.cpp

@@ -0,0 +1,50 @@
+// Test without serialization:
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
+// RUN:            -ast-dump %s -ast-dump-filter Test \
+// RUN: | FileCheck --strict-whitespace --match-full-lines %s
+//
+// Test with serialization:
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 -emit-pch -o %t %s
+// RUN: %clang_cc1 -x c++ -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
+// RUN:           -include-pch %t -ast-dump-all -ast-dump-filter Test /dev/null \
+// RUN: | sed -e "s/ <undeserialized declarations>//" -e "s/ imported//" \
+// RUN: | FileCheck --strict-whitespace --match-full-lines %s
+
+int i;
+struct S {
+  int i;
+  int ii;
+};
+S s;
+
+struct F {
+  char padding[12];
+  S s;
+};
+F f;
+
+void Test() {
+  constexpr int *pi = &i;
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} pi 'int *const' constexpr cinit
+  // CHECK-NEXT:  |   |-value: LValue Base=VarDecl {{.*}}, Null=0, Offset=0, HasPath=1, PathLength=0, Path=()
+
+  constexpr int *psi = &s.i;
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} psi 'int *const' constexpr cinit
+  // CHECK-NEXT:  |   |-value: LValue Base=VarDecl {{.*}}, Null=0, Offset=0, HasPath=1, PathLength=1, Path=({{.*}})
+
+  constexpr int *psii = &s.ii;
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} psii 'int *const' constexpr cinit
+  // CHECK-NEXT:  |   |-value: LValue Base=VarDecl {{.*}}, Null=0, Offset=4, HasPath=1, PathLength=1, Path=({{.*}})
+
+  constexpr int *pf = &f.s.ii;
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} pf 'int *const' constexpr cinit
+  // CHECK-NEXT:  |   |-value: LValue Base=VarDecl {{.*}}, Null=0, Offset=12, HasPath=1, PathLength=2, Path=({{.*}}, {{.*}})
+
+  constexpr char *pc = &f.padding[2];
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} pf 'char *const' constexpr cinit
+  // CHECK-NEXT:  |   |-value: LValue Base=VarDecl {{.*}}, Null=0, Offset=2, HasPath=1, PathLength=2, Path=({{.*}}, 2)
+
+  constexpr const int *n = nullptr;
+  // CHECK:    `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} n 'const int *const' constexpr cinit
+  // CHECK-NEXT:      |-value: LValue Base=null, Null=1, Offset=0, HasPath=1, PathLength=0, Path=()
+}

clang/test/AST/ast-dump-APValue-todo.cpp

@@ -16,10 +16,6 @@ struct S {
 };
 
 void Test() {
-  constexpr int *pi = &i;
-  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} pi 'int *const' constexpr cinit
-  // CHECK-NEXT:  |   |-value: LValue <todo>
-
   constexpr int(S::*pmi) = &S::i;
   // CHECK:    `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} pmi 'int (S::*const)' constexpr cinit
   // CHECK-NEXT:      |-value: MemberPointer <todo>