Disable terser conditional optimization (#39279)

* Disable optimization of conditionals

This prevents optimizations such as converting:

condition ? __( 'true', 'domain' ) : __( 'false', 'domain' );

to

__(o?'true':'false','domain' );

which is an invalid optimization for translatable strings

* changelog

* Update tests now that Terser's conditional optimization has been disabled

* changelog

* Remove documentation about unnecessary workaround

projects/js-packages/i18n-check-webpack-plugin/README.md

@@ -102,37 +102,6 @@ Instead put it inside the property:
 />
 ```
 
-### Conditional function call compaction
-
-When a conditional calls the same function in each branch with only one argument different, Terser will transform it to a single call with the condition inside the argument. For example, either of these
-```js
-example = flag ? __( 'Flag is set', 'domain' ) : __( 'Flag is not set', 'domain' );
-```
-```js
-if ( flag ) {
-	example = __( 'Flag is set', 'domain' );
-} else {
-	example = __( 'Flag is not set', 'domain' );
-}
-```
-will become
-```js
-example = __( flag ? 'Flag is set' : 'Flag is not set', 'domain' );
-```
-which will result in neither string being detected for translation.
-
-You can fix this by making the calls less similar, for example by adding a dummy argument to one call
-```js
-example = flag ? __( 'Flag is set', 'domain' ) : __( 'Flag is not set', 'domain', /* dummy arg to avoid bad minification */ 0 );
-```
-or by specifying an unnecessary context in one call (or a different context in both)
-```js
-example = flag ? __( 'Flag is set', 'domain' ) : _x( 'Flag is not set', '', 'domain' );
-```
-```js
-example = flag ? _x( 'Flag is set', 'Something', 'domain' ) : _x( 'Flag is not set', 'Something different', 'domain' );
-```
-
 ### Pruned branches and common strings
 
 In some cases, such as when `process.env.NODE_ENV` is tested or when ES module tree-shaking is done, code paths can be known to be unreachable. For example, only one branch in the following will be kept:

projects/js-packages/i18n-check-webpack-plugin/changelog/fix-etk-translation-issues

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Updated tests now that Terser's conditionals' optimization is disabled

projects/js-packages/i18n-check-webpack-plugin/tests/__snapshots__/build.test.js.snap

@@ -102,9 +102,6 @@ exports[`Webpack \`known-problems\`: Webpack build files 1`] = `
 exports[`Webpack \`known-problems\`: Webpack build stats 1`] = `
 {
   "errors": [
-    {
-      "message": "main.js:3:148: msgid argument is not a string literal: __(o?"Foo is set":"Foo is not set","domain")",
-    },
     {
       "message": "main.js: Translator comments have gone missing for "The comment will be lost when the assignment is merged into the above const" (context "context")
  - Translators: This comment will be lost",
@@ -113,11 +110,6 @@ exports[`Webpack \`known-problems\`: Webpack build stats 1`] = `
       "message": "main.js: Translator comments have gone missing for "This is another workaround" (context "context")
  - Translators: This comment will be in the source but not detected for the right message.",
     },
-    {
-      "message": "main.js: Optimization seems to have broken the following translation strings:
- - "Foo is not set"
- - "Foo is set"",
-    },
   ],
   "warnings": [],
 }
@@ -165,245 +157,32 @@ exports[`Webpack \`options-filter\`: Webpack build stats 1`] = `
 {
   "children": [
     {
-      "errors": [
-        {
-          "message": "string/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-        },
-        {
-          "message": "string/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-        },
-        {
-          "message": "string/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-        },
-        {
-          "message": "string/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-        },
-        {
-          "message": "string/main.js: Optimization seems to have broken the following translation strings:
- - "string is not set"
- - "string is set"",
-        },
-      ],
+      "errors": [],
       "name": "string",
       "warnings": [],
     },
     {
-      "errors": [
-        {
-          "message": "regex/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-        },
-        {
-          "message": "regex/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-        },
-        {
-          "message": "regex/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-        },
-        {
-          "message": "regex/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-        },
-        {
-          "message": "regex/main.js: Optimization seems to have broken the following translation strings:
- - "regex is not set"
- - "regex is set"",
-        },
-      ],
+      "errors": [],
       "name": "regex",
       "warnings": [],
     },
     {
-      "errors": [
-        {
-          "message": "function/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-        },
-        {
-          "message": "function/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-        },
-        {
-          "message": "function/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-        },
-        {
-          "message": "function/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-        },
-        {
-          "message": "function/main.js: Optimization seems to have broken the following translation strings:
- - "func is not set"
- - "func is set"",
-        },
-      ],
+      "errors": [],
       "name": "function",
       "warnings": [],
     },
     {
-      "errors": [
-        {
-          "message": "array/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-        },
-        {
-          "message": "array/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-        },
-        {
-          "message": "array/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-        },
-        {
-          "message": "array/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-        },
-        {
-          "message": "array/main.js: Optimization seems to have broken the following translation strings:
- - "arr is not set"
- - "arr is set"",
-        },
-      ],
+      "errors": [],
       "name": "array",
       "warnings": [],
     },
     {
-      "errors": [
-        {
-          "message": "undefined/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-        },
-        {
-          "message": "undefined/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-        },
-        {
-          "message": "undefined/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-        },
-        {
-          "message": "undefined/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-        },
-        {
-          "message": "undefined/main.js: Optimization seems to have broken the following translation strings:
- - "arr is not set"
- - "arr is set"
- - "func is not set"
- - "func is set"
- - "regex is not set"
- - "regex is set"
- - "string is not set"
- - "string is set"",
-        },
-      ],
+      "errors": [],
       "name": "undefined",
       "warnings": [],
     },
   ],
-  "errors": [
-    {
-      "compilerPath": "string",
-      "message": "string/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-    },
-    {
-      "compilerPath": "string",
-      "message": "string/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-    },
-    {
-      "compilerPath": "string",
-      "message": "string/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-    },
-    {
-      "compilerPath": "string",
-      "message": "string/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-    },
-    {
-      "compilerPath": "string",
-      "message": "string/main.js: Optimization seems to have broken the following translation strings:
- - "string is not set"
- - "string is set"",
-    },
-    {
-      "compilerPath": "regex",
-      "message": "regex/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-    },
-    {
-      "compilerPath": "regex",
-      "message": "regex/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-    },
-    {
-      "compilerPath": "regex",
-      "message": "regex/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-    },
-    {
-      "compilerPath": "regex",
-      "message": "regex/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-    },
-    {
-      "compilerPath": "regex",
-      "message": "regex/main.js: Optimization seems to have broken the following translation strings:
- - "regex is not set"
- - "regex is set"",
-    },
-    {
-      "compilerPath": "function",
-      "message": "function/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-    },
-    {
-      "compilerPath": "function",
-      "message": "function/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-    },
-    {
-      "compilerPath": "function",
-      "message": "function/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-    },
-    {
-      "compilerPath": "function",
-      "message": "function/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-    },
-    {
-      "compilerPath": "function",
-      "message": "function/main.js: Optimization seems to have broken the following translation strings:
- - "func is not set"
- - "func is set"",
-    },
-    {
-      "compilerPath": "array",
-      "message": "array/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-    },
-    {
-      "compilerPath": "array",
-      "message": "array/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-    },
-    {
-      "compilerPath": "array",
-      "message": "array/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-    },
-    {
-      "compilerPath": "array",
-      "message": "array/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-    },
-    {
-      "compilerPath": "array",
-      "message": "array/main.js: Optimization seems to have broken the following translation strings:
- - "arr is not set"
- - "arr is set"",
-    },
-    {
-      "compilerPath": "undefined",
-      "message": "undefined/main.js:1:76: msgid argument is not a string literal: __(t?"arr is set":"arr is not set","domain")",
-    },
-    {
-      "compilerPath": "undefined",
-      "message": "undefined/main.js:1:186: msgid argument is not a string literal: __(t?"func is set":"func is not set","domain")",
-    },
-    {
-      "compilerPath": "undefined",
-      "message": "undefined/main.js:1:374: msgid argument is not a string literal: __(t?"regex is set":"regex is not set","domain")",
-    },
-    {
-      "compilerPath": "undefined",
-      "message": "undefined/main.js:1:488: msgid argument is not a string literal: __(t?"string is set":"string is not set","domain")",
-    },
-    {
-      "compilerPath": "undefined",
-      "message": "undefined/main.js: Optimization seems to have broken the following translation strings:
- - "arr is not set"
- - "arr is set"
- - "func is not set"
- - "func is set"
- - "regex is not set"
- - "regex is set"
- - "string is not set"
- - "string is set"",
-    },
-  ],
+  "errors": [],
   "warnings": [],
 }
 `;
@@ -420,16 +199,7 @@ exports[`Webpack \`options-warnOnly\`: Webpack build files 1`] = `
 exports[`Webpack \`options-warnOnly\`: Webpack build stats 1`] = `
 {
   "errors": [],
-  "warnings": [
-    {
-      "message": "main.js:1:77: msgid argument is not a string literal: __(t?"X is set":"X is not set","domain")",
-    },
-    {
-      "message": "main.js: Optimization seems to have broken the following translation strings:
- - "X is not set"
- - "X is set"",
-    },
-  ],
+  "warnings": [],
 }
 `;
 

projects/js-packages/webpack-config/changelog/fix-etk-translation-issues

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Prevents an optimization of conditionals which breaks translatable strings

projects/js-packages/webpack-config/src/webpack/terser.js

@@ -59,6 +59,9 @@ const defaultOptions = {
 				`${ isTranslatorsComment }; return isTranslatorsComment( comment )`
 			),
 		},
+		compress: {
+			conditionals: false,
+		},
 	},
 	// Same.
 	extractComments: new Function(