[BUG] npm --save-dev does not infer --save

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

When I run npm install --save-dev <package-name> package.json is not modified; nothing is added to devDependencies.

Expected Behavior

I would expect that a command like npm install --save-dev <package-name> would install that package in the current directory and add the package information in package.json's devDepencies object.

Steps To Reproduce

1. In this environment...

[~/test]$ npm -v
8.15.0
[~/test]$ node -v 
v18.7.0
[~/test]$ sw_vers
ProductName:	macOS
ProductVersion:	12.4
BuildVersion:	21F79

2. With this config...

$ npm config list
package-lock = false 
save = false 
save-exact = false 
save-prefix = "^" 

5. Run '...'

[~/test]$ rm -rf package.json 
[~/test]$ rm -rf node_modules 
[~/test]$ npm init -y
Wrote to /Users/matt/test/package.json:

{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}


[~/test]$ npm install --save-dev mocha

added 79 packages, and audited 80 packages in 6s

20 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities
[~/test]$ cat package.json 
{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}
[~/test]$

4. See error...
   devDependencies does not exist as expected.

Environment

• npm: 8.15.0
• Node.js: 18.7.0
• OS Name: macOS 12.4
• System Model Name:
• npm config:

package-lock = false 
save = false 
save-exact = false 
save-prefix = "^" 

Reproduce the command using npm 8.15.0, Node.js 18.7.0, and the listed npm configuration, then inspect the generated package.json. Compare the --save-dev result with the expected devDependencies entry; done means a regression test or confirmed behavior clearly covers this case.