[Clang][DebugInfo] Clang generates an extra spurious unnamed 'dbg.declare'.

Do not emit call to llvm.dbg.declare when the variable declaration
is a DecompositionDecl as its instance class is always unnamed.

The emitted debug declare looks like:

  call void @llvm.dbg.declare(metadata ..., metadata !xx, metadata ...)
  !xx = !DILocalVariable(scope: !..., file: !..., line: ..., type: !...)

- Remove the added test case.
- Added the '--implicit-check-not' option
- Added checks for variables names.

Author: CarlosAlbertoEnciso

clang/test/CodeGenCXX/debug-info-structured-binding-field.cpp

@@ -1,9 +1,15 @@
-// RUN: %clang_cc1 -emit-llvm -debug-info-kind=standalone -triple %itanium_abi_triple %s -o - | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -debug-info-kind=standalone -triple %itanium_abi_triple %s -o - | FileCheck %s --implicit-check-not="call void @llvm.dbg.declare"
+
+// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[a-z]+}}, metadata !{{[0-9]+}}, metadata !DIExpression())
+// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata ![[VAR_1:[0-9]+]], metadata !DIExpression())
+// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata ![[VAR_2:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, {{[0-9]+}}))
+// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata ![[VAR_3:[0-9]+]], metadata !DIExpression(DW_OP_deref))
+// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata ![[VAR_4:[0-9]+]], metadata !DIExpression(DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}))
+// CHECK: ![[VAR_1]] = !DILocalVariable(name: "x1"
+// CHECK: ![[VAR_2]] = !DILocalVariable(name: "y1"
+// CHECK: ![[VAR_3]] = !DILocalVariable(name: "x2"
+// CHECK: ![[VAR_4]] = !DILocalVariable(name: "y2"
 
-// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata !{{[0-9]+}}, metadata !DIExpression())
-// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_plus_uconst, {{[0-9]+}}))
-// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_deref))
-// CHECK: call void @llvm.dbg.declare(metadata ptr %{{[0-9]+}}, metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}))
 struct A {
   int x;
   int y;