[FIX] qweb: correctly capture the scope of arrow functions in props

src/component/directive.ts

@@ -234,7 +234,11 @@ QWeb.addDirective({
       } else if (!name.startsWith("t-")) {
         if (name !== "class" && name !== "style") {
           // this is a prop!
-          props[name] = ctx.formatExpression(value) || "undefined";
+          if (value.includes("=>")) {
+            props[name] = ctx.captureExpression(value);
+          } else {
+            props[name] = ctx.formatExpression(value) || "undefined";
+          }
         }
       }
     }

src/qweb/compilation_context.ts

@@ -163,7 +163,18 @@ export class CompilationContext {
     const done = new Set();
     return tokens
       .map((tok) => {
-        if (tok.varName) {
+        // "this" in captured expressions should be the current component
+        if (tok.value === "this") {
+          if (!done.has("this")) {
+            done.add("this");
+            this.addLine(`const this_${argId} = utils.getComponent(context);`);
+          }
+          tok.value = `this_${argId}`;
+        }
+        // Variables that should be looked up in the scope. isLocal is for arrow
+        // function arguments that should stay untouched (eg "ev => ev" should
+        // not become "const ev_1 = scope['ev']; ev_1 => ev_1")
+        if (tok.varName && !tok.isLocal) {
           if (!done.has(tok.varName)) {
             done.add(tok.varName);
             this.addLine(`const ${tok.varName}_${argId} = ${tok.value};`);

src/qweb/expression_parser.ts

@@ -70,6 +70,7 @@ interface Token {
   size?: number;
   varName?: string;
   replace?: Function;
+  isLocal?: boolean;
 }
 
 const STATIC_TOKEN_MAP: { [key: string]: TKind } = Object.assign(Object.create(null), {
@@ -254,6 +255,7 @@ const isRightSeparator = (token) =>
  * the list of variables so it does not get replaced by a lookup in the context
  */
 export function compileExprToArray(expr: string, scope: { [key: string]: QWebVar }): Token[] {
+  const localVars = new Set<string>();
   scope = Object.create(scope);
   const tokens = tokenize(expr);
 
@@ -308,11 +310,13 @@ export function compileExprToArray(expr: string, scope: { [key: string]: QWebVar
           if (tokens[j].type === "SYMBOL" && tokens[j].originalValue) {
             tokens[j].value = tokens[j].originalValue!;
             scope[tokens[j].value] = { id: tokens[j].value, expr: tokens[j].value };
+            localVars.add(tokens[j].value);
           }
           j--;
         }
       } else {
         scope[token.value] = { id: token.value, expr: token.value };
+        localVars.add(token.value);
       }
     }
 
@@ -327,6 +331,13 @@ export function compileExprToArray(expr: string, scope: { [key: string]: QWebVar
     }
     i++;
   }
+  // Mark all variables that have been used locally.
+  // This assumes the expression has only one scope (incorrect but "good enough for now")
+  for (const token of tokens) {
+    if (token.type === "SYMBOL" && localVars.has(token.value)) {
+      token.isLocal = true;
+    }
+  }
   return tokens;
 }