Fix unignore statements breaking file filtering

shared/configs.ts

@@ -1,7 +1,7 @@
 import type { FlatConfigItem, MatchedFile } from './types'
 import { Minimatch } from 'minimatch'
 
-const minimatchOpts = { dot: true }
+const minimatchOpts = { dot: true, flipNegate: true }
 const _matchInstances = new Map<string, Minimatch>()
 
 function minimatch(file: string, pattern: string) {
@@ -13,8 +13,9 @@ function minimatch(file: string, pattern: string) {
   return m.match(file)
 }
 
-export function getMatchedGlobs(file: string, glob: (string | string[])[]) {
+function getMatchedGlobs(file: string, glob: (string | string[])[]) {
   const globs = (Array.isArray(glob) ? glob : [glob]).flat()
+  // Strip leading `!` from globs since they don't mean invert the match condition, but rather unignore
   return globs.filter(glob => minimatch(file, glob)).flat()
 }
 
@@ -35,12 +36,24 @@ export function isGeneralConfig(config: FlatConfigItem) {
   return (!config.files && !config.ignores) || isIgnoreOnlyConfig(config)
 }
 
+/**
+ * Given a list of matched globs, if an unignore (leading !) is the last one, then the file no longer matches the glob set
+ */
+function filterUnignoreGlobs(globs: string[]) {
+  if (!globs.length)
+    return globs
+  if (globs[globs.length - 1].startsWith('!'))
+    return []
+  return globs
+}
+
 export function matchFile(
   filepath: string,
   configs: FlatConfigItem[],
   ignoreOnlyConfigs: FlatConfigItem[],
 ): MatchedFile {
-  const globalIgnored = ignoreOnlyConfigs.flatMap(config => getMatchedGlobs(filepath, config.ignores!))
+  const globalIgnored = ignoreOnlyConfigs.flatMap(config => filterUnignoreGlobs(getMatchedGlobs(filepath, config.ignores!)))
+
   if (globalIgnored.length) {
     return {
       filepath,
@@ -56,7 +69,8 @@ export function matchFile(
   }
   configs.forEach((config, index) => {
     const positive = getMatchedGlobs(filepath, config.files || [])
-    const negative = getMatchedGlobs(filepath, config.ignores || [])
+    const negative = filterUnignoreGlobs(getMatchedGlobs(filepath, config.ignores || []))
+
     if (!negative.length && positive.length)
       result.configs.push(index)
     result.globs.push(