Look at constant Go regular expressions on GitHub and see if they match an optim

regexp-optim-github.sql

  # Analyse impact of https://github.com/golang/go/issues/21463
  # using BigQuery GitHub public dataset.
  
  # To run on the entire GitHub corpus, 
  # remove the `sample_` prefix from the table names.
  # Warning: This query processes ~2.2 TB of data, which is above BigQuery free quota.
  
SELECT
  applies,
  COUNT(*) AS cnt
FROM (
  SELECT
    CASE
      WHEN REGEXP_MATCH(reg, r'[\*\+\?]') THEN "no: [\\*\\+\\?]"
      WHEN REGEXP_MATCH(reg, r'\^[\w\d\s\.]+$') THEN "yes: \\^[\\w\\d\\s\\.]+$"
      WHEN REGEXP_MATCH(reg, r'[\w\d\s\.]+\$') THEN "yes: [\\w\\d\\s\\.]+\\$"
      WHEN REGEXP_MATCH(reg, r'^([\w\d\s]+\|?)+$') THEN "yes: ^([\\w\\d\\s]+\\|?)+$"
      WHEN REGEXP_MATCH(reg, r'^[^\^\$]+$') THEN "no: ^[^\\^\\$]+$"
      ELSE "maybe"
    END AS applies,
    reg
  FROM (
    SELECT
      REGEXP_EXTRACT(content, r'.MatchString\("(.*)", ') AS reg
    FROM (
      SELECT
        id,
        SPLIT(content, "regexp") AS content
      FROM
        [bigquery-public-data:github_repos.sample_contents]
      WHERE
        REGEXP_MATCH(content, r'regexp.MatchString\("')) AS C
    JOIN (
      SELECT
        id
      FROM
        [bigquery-public-data:github_repos.sample_files]
      WHERE
        path LIKE '%.go'
      GROUP BY
        id) AS F
    ON
      C.id = F.id) )
WHERE reg != "null"
GROUP BY
  applies
ORDER BY
  applies DESC

For anyone wanting to run this query - try extracting all the .go files first, or use the extract I left at https://bigquery.cloud.google.com/table/fh-bigquery:github_extracts.contents_go.

(avoid querying [bigquery-public-data:github_repos.sample_contents] as it's too big, and full of not .go content)