feat(cli): allow overriding

src/main/options-normalizer.js

@@ -158,6 +158,18 @@ function optionInfoToSchema(optionInfo, { isCLI, optionInfos }) {
     handlers.deprecated = true;
   }
 
+  // allow CLI overriding, e.g., prettier package.json --tab-width 1 --tab-width 2
+  if (isCLI && !optionInfo.array) {
+    const originalPreprocess = parameters.preprocess || (x => x);
+    parameters.preprocess = (value, schema, utils) =>
+      schema.preprocess(
+        originalPreprocess(
+          Array.isArray(value) ? value[value.length - 1] : value
+        ),
+        utils
+      );
+  }
+
   return optionInfo.array
     ? vnopts.ArraySchema.create(
         Object.assign(

tests_integration/__tests__/__snapshots__/arg-parsing.js.snap

@@ -1,5 +1,9 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`allow overriding flags (stderr) 1`] = `""`;
+
+exports[`allow overriding flags (write) 1`] = `Array []`;
+
 exports[`boolean flags do not swallow the next argument (stderr) 1`] = `""`;
 
 exports[`boolean flags do not swallow the next argument (stdout) 1`] = `

tests_integration/__tests__/arg-parsing.js

@@ -37,3 +37,14 @@ describe("deprecated option values are warned", () => {
     status: 0
   });
 });
+
+describe("allow overriding flags", () => {
+  runPrettier(
+    "cli/arg-parsing",
+    ["--tab-width=1", "--tab-width=3", "--parser=babylon"],
+    { input: "function a() { b }" }
+  ).test({
+    stdout: "function a() {\n   b;\n}\n",
+    status: 0
+  });
+});