R code linting (diagnostics) is provided by lintr via language server and is enabled by default. It provides syntax error warnings as well as style guidelines.

To disable diagnostics, you might add the following to the VS Code settings:

{
  "r.lsp.diagnostics": false
}

However, you will not be notified if syntax errors in the code are detected.

The default linting behaviour is based on the tidyverse style guide, which you may not find to your liking. To customize, you should create/edit the global lintr config file at ~/.lintr. Alternatively, you can also create/edit a project-specific lintr config file at ${workspaceFolder}/.lintr. Some example of customized lintr files are provided below.

• Visit Individual linters for a complete list of supported linters.
• Visit the Configuring linters for a complete guide to customizing lintr config regarding the list of linters and file or line exclusions.

linters: list()

Adjust the number of characters in each line for line_length_linter and disable commented_code_linter.

linters: linters_with_defaults(
    line_length_linter(120), 
    commented_code_linter = NULL
  )

(Note: the leading space in front of the final parenthesis is deliberate, since it is required for the DCF format.)

A more aggressive example, turning off the <- assignment linter (i.e., = is fine) among other things. Background here.

linters: linters_with_defaults(
   line_length_linter    = NULL, # note: vscode-R default is 120
   cyclocomp_linter      = NULL, # same as vscode-R
   object_name_linter    = NULL, # same as vscode-R
   object_usage_linter   = NULL, # same as vscode-R
   commented_code_linter = NULL,
   assignment_linter     = NULL,
   quotes_linter         = NULL,
   semicolon_linter      = NULL,
   seq_linter            = NULL,
   indentation_linter    = NULL
  )

linters: list(
  commas_linter(),
  duplicate_argument_linter(),
  missing_argument_linter(),
  missing_package_linter(),
  namespace_linter())