[環境]
$ uname -a
Linux salty-VirtualBox 5.4.0-71-generic #79~18.04.1-Ubuntu SMP Thu Mar 25 05:45:39 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ clang++ -v
clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

Visual Stdio Code
バージョン 1.55.s
[解決方法]
以下の2つが必要です。
(1) コンパイルするときのオプションに「-D_GLIBCXX_DEBUG」を追加する
			"linux": {
				"MIMode": "gdb",
				"setupCommands": [
						{ "text": "-enable-pretty-printing", "description": "enable pretty printing", "ignoreFailures": true },
						{ "text": "handle SIGPIPE nostop noprint pass", "description": "ignore SIGPIPE", "ignoreFailures": true }  
				]
			},