Fix false positives in no-unused-svelte-ignore (#88)

Author: ota-meshi

src/rules/no-unused-svelte-ignore.ts

@@ -113,9 +113,14 @@ export default createRule("no-unused-svelte-ignore", {
     if (!ignoreComments.length) {
       return {}
     }
-    for (const warning of getSvelteCompileWarnings(context, {
+    const warnings = getSvelteCompileWarnings(context, {
+      warnings: "onlyWarnings",
       removeComments: new Set(ignoreComments.map((i) => i.token)),
-    })) {
+    })
+    if (!warnings) {
+      return {}
+    }
+    for (const warning of warnings) {
       if (!warning.code) {
         continue
       }

src/rules/valid-compile.ts

@@ -49,7 +49,11 @@ export default createRule("valid-compile", {
 
     return {
       "Program:exit"() {
-        report(getSvelteCompileWarnings(context, { ignoreWarnings }))
+        report(
+          getSvelteCompileWarnings(context, {
+            warnings: ignoreWarnings ? "ignoreWarnings" : null,
+          })!,
+        )
       },
     }
   },

src/shared/svelte-compile-warns.ts

@@ -23,7 +23,7 @@ export type Warning = {
   message: string
 } & Loc
 export type GetSvelteWarningsOption = {
-  ignoreWarnings?: boolean
+  warnings: "ignoreWarnings" | "onlyWarnings" | null
   removeComments?: Iterable<AST.Token | AST.Comment>
 }
 
@@ -33,7 +33,7 @@ export type GetSvelteWarningsOption = {
 export function getSvelteCompileWarnings(
   context: RuleContext,
   option: GetSvelteWarningsOption,
-): Warning[] {
+): Warning[] | null {
   const sourceCode = context.getSourceCode()
   const text = !option.removeComments
     ? sourceCode.text
@@ -259,10 +259,14 @@ export function getSvelteCompileWarnings(
       }
     }
   }
-
   const code = remapContext.postprocess()
+  const baseWarnings = getWarningsFromCode(code, option)
+  if (!baseWarnings) {
+    return null
+  }
+
   const warnings: Warning[] = []
-  for (const warn of getWarningsFromCode(code, option)) {
+  for (const warn of baseWarnings) {
     let loc: Loc | null = null
 
     /** Get re-mapped location */
@@ -296,8 +300,10 @@ type TS = typeof typescript
  */
 function getWarningsFromCode(
   code: string,
-  { ignoreWarnings }: { ignoreWarnings?: boolean },
-): Warning[] {
+  { warnings }: GetSvelteWarningsOption,
+): Warning[] | null {
+  const ignoreWarnings = warnings === "ignoreWarnings"
+  const onlyWarnings = warnings === "onlyWarnings"
   try {
     const result = compiler.compile(code, {
       generate: false,
@@ -309,6 +315,9 @@ function getWarningsFromCode(
     return result.warnings as Warning[]
     // eslint-disable-next-line @typescript-eslint/no-explicit-any -- ignore
   } catch (e: any) {
+    if (onlyWarnings) {
+      return null
+    }
     // console.log(code)
     if (!ignoreWarnings) {
       try {

tests/fixtures/rules/no-unused-svelte-ignore/valid/has-error-input.svelte

@@ -0,0 +1,8 @@
+<script>
+  let foo
+</script>
+
+<slot name="default" />
+
+<!-- svelte-ignore a11y-autofocus -->
+<img src="foo" />