[NFC] Remove forEachSourceFileIn

We actually wanted to use forEachFileToTypeCheck, which will restrict
the source files we analyze to just the given primaries in incremental
mode, and the whole module's source files otherwise.

Author: CodaFi

lib/Frontend/Frontend.cpp

@@ -862,19 +862,16 @@ bool CompilerInstance::loadPartialModulesAndImplicitImports() {
   return hadLoadError;
 }
 
-static void
-forEachSourceFileIn(ModuleDecl *module,
-                    llvm::function_ref<void(SourceFile &)> fn) {
-  for (auto fileName : module->getFiles()) {
-    if (auto SF = dyn_cast<SourceFile>(fileName))
-      fn(*SF);
-  }
-}
-
 void CompilerInstance::forEachFileToTypeCheck(
     llvm::function_ref<void(SourceFile &)> fn) {
   if (isWholeModuleCompilation()) {
-    forEachSourceFileIn(MainModule, [&](SourceFile &SF) { fn(SF); });
+    for (auto fileName : MainModule->getFiles()) {
+      auto *SF = dyn_cast<SourceFile>(fileName);
+      if (!SF) {
+        continue;
+      }
+      fn(*SF);
+    }
   } else {
     for (auto *SF : PrimarySourceFiles) {
       fn(*SF);
@@ -883,7 +880,7 @@ void CompilerInstance::forEachFileToTypeCheck(
 }
 
 void CompilerInstance::finishTypeChecking() {
-  forEachSourceFileIn(MainModule, [&](SourceFile &SF) {
+  forEachFileToTypeCheck([](SourceFile &SF) {
     performWholeModuleTypeChecking(SF);
   });
 }