Verify if one or more files are emitting into same output file we provide error

tests/baselines/reference/filesEmittingIntoSameOutput.errors.txt

@@ -0,0 +1,12 @@
+error TS5056: Cannot write file 'tests/cases/compiler/a.js' since one or more input files would emit into it.
+
+
+!!! error TS5056: Cannot write file 'tests/cases/compiler/a.js' since one or more input files would emit into it.
+==== tests/cases/compiler/a.ts (0 errors) ====
+    class c {
+    }
+    
+==== tests/cases/compiler/a.tsx (0 errors) ====
+    function foo() {
+    }
+    

tests/baselines/reference/filesEmittingIntoSameOutputWithOutOption.errors.txt

@@ -0,0 +1,12 @@
+error TS5056: Cannot write file 'tests/cases/compiler/a.js' since one or more input files would emit into it.
+
+
+!!! error TS5056: Cannot write file 'tests/cases/compiler/a.js' since one or more input files would emit into it.
+==== tests/cases/compiler/a.ts (0 errors) ====
+    export class c {
+    }
+    
+==== tests/cases/compiler/b.ts (0 errors) ====
+    function foo() {
+    }
+    

tests/cases/compiler/filesEmittingIntoSameOutput.ts

@@ -0,0 +1,7 @@
+// @filename: a.ts
+class c {
+}
+
+// @filename: a.tsx
+function foo() {
+}

tests/cases/compiler/filesEmittingIntoSameOutputWithOutOption.ts

@@ -0,0 +1,9 @@
+// @out: tests/cases/compiler/a.js
+// @module: amd
+// @filename: a.ts
+export class c {
+}
+
+// @filename: b.ts
+function foo() {
+}