repl: Mitigate vm #548 function redefinition issue

```js node 🙈 ₹ git:(upstream ⚡ repl-tmp-548) ./node > function name(){return "node"}; undefined > name() 'node' > function name(){return "nodejs"}; undefined > name() 'nodejs' > ``` PR-URL: #7794 Reviewed-By: Evan Lucas <[email protected]>

Author: princejwesley

lib/repl.js

@@ -471,19 +471,7 @@ function REPLServer(prompt,
 }
 
 varevalCmd=self.bufferedCommand+cmd;
-if(/^\s*\{/.test(evalCmd)&&/\}\s*$/.test(evalCmd)){
-// It's confusing for `{a : 1 }` to be interpreted as a block
-// statement rather than an object literal. So, we first try
-// to wrap it in parentheses, so that it will be interpreted as
-// an expression.
-evalCmd='('+evalCmd+')\n';
-self.wrappedCmd=true;
-}else{
-// otherwise we just append a \n so that it will be either
-// terminated, or continued onto the next expression if it's an
-// unexpected end of input.
-evalCmd=evalCmd+'\n';
-}
+evalCmd=preprocess(evalCmd);
 
 debug('eval %j',evalCmd);
 self.eval(evalCmd,self.context,'repl',finish);
@@ -538,6 +526,26 @@ function REPLServer(prompt,
 // Display prompt again
 self.displayPrompt();
 }
+
+functionpreprocess(code){
+letcmd=code;
+if(/^\s*\{/.test(cmd)&&/\}\s*$/.test(cmd)){
+// It's confusing for `{a : 1 }` to be interpreted as a block
+// statement rather than an object literal. So, we first try
+// to wrap it in parentheses, so that it will be interpreted as
+// an expression.
+cmd=`(${cmd})`;
+self.wrappedCmd=true;
+}else{
+// Mitigate https://github.com/nodejs/node/issues/548
+cmd=cmd.replace(/^\s*function\s+([^(]+)/,
+(_,name)=>`var ${name} = function ${name}`);
+}
+// Append a \n so that it will be either
+// terminated, or continued onto the next expression if it's an
+// unexpected end of input.
+return`${cmd}\n`;
+}
 });
 
 self.on('SIGCONT',function(){

test/known_issues/test-repl-function-redefinition-edge-case.js

@@ -0,0 +1,38 @@
+// Reference: https://github.com/nodejs/node/pull/7624
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+constrepl=require('repl');
+conststream=require('stream');
+
+common.globalCheck=false;
+
+constr=initRepl();
+
+r.input.emit('data','function a(){return 42} (1)\n');
+r.input.emit('data','a\n');
+r.input.emit('data','.exit');
+
+constexpected='1\n[Function a]\n';
+constgot=r.output.accumulator.join('');
+assert.strictEqual(got,expected);
+
+functioninitRepl(){
+constinput=newstream();
+input.write=input.pause=input.resume=()=>{};
+input.readable=true;
+
+constoutput=newstream();
+output.writable=true;
+output.accumulator=[];
+
+output.write=(data)=>output.accumulator.push(data);
+
+returnrepl.start({
+ input,
+ output,
+useColors: false,
+terminal: false,
+prompt: ''
+});
+}

test/parallel/test-repl.js

@@ -328,6 +328,11 @@ function error_test(){
 // or block comment. https://github.com/nodejs/node/issues/3611
 {client: client_unix,send: 'a = 3.5e',
 expect: /^SyntaxError:UnexpectedtokenILLEGAL/},
+// Mitigate https://github.com/nodejs/node/issues/548
+{client: client_unix,send: 'function name(){return "node"};name()',
+expect: "'node'\n"+prompt_unix},
+{client: client_unix,send: 'function name(){return "nodejs"};name()',
+expect: "'nodejs'\n"+prompt_unix},
 ]);
 }