[Sema|NFC] Refactor findInconsistentImports

Break findInconsistentImportsAcrossFile into two services, one finding
inconsistencies across a whole module and a new one finding them across
a single file.

Author: xymus

lib/Sema/ImportResolution.cpp

@@ -749,54 +749,66 @@ static bool moduleHasAnyImportsMatchingFlag(ModuleDecl *mod, ImportFlags flag) {
   return false;
 }
 
-/// Finds all import declarations for a single module that inconsistently match
+/// Finds all import declarations for a single file that inconsistently match
 /// \c predicate and passes each pair of inconsistent imports to \c diagnose.
 template <typename Pred, typename Diag>
-static void findInconsistentImports(ModuleDecl *mod, Pred predicate,
-                                    Diag diagnose) {
-  llvm::DenseMap<ModuleDecl *, const ImportDecl *> matchingImports;
-  llvm::DenseMap<ModuleDecl *, std::vector<const ImportDecl *>> otherImports;
+static void findInconsistentImportsAcrossFile(
+    const SourceFile *SF, Pred predicate, Diag diagnose,
+    llvm::DenseMap<ModuleDecl *, const ImportDecl *> &matchingImports,
+    llvm::DenseMap<ModuleDecl *, std::vector<const ImportDecl *>> &otherImports) {
+
+  for (auto *topLevelDecl : SF->getTopLevelDecls()) {
+    auto *nextImport = dyn_cast<ImportDecl>(topLevelDecl);
+    if (!nextImport)
+      continue;
 
-  for (const FileUnit *file : mod->getFiles()) {
-    auto *SF = dyn_cast<SourceFile>(file);
-    if (!SF)
+    ModuleDecl *module = nextImport->getModule();
+    if (!module)
       continue;
 
-    for (auto *topLevelDecl : SF->getTopLevelDecls()) {
-      auto *nextImport = dyn_cast<ImportDecl>(topLevelDecl);
-      if (!nextImport)
+    if (predicate(nextImport)) {
+      // We found a matching import.
+      bool isNew = matchingImports.insert({module, nextImport}).second;
+      if (!isNew)
         continue;
 
-      ModuleDecl *module = nextImport->getModule();
-      if (!module)
-        continue;
+      auto seenOtherImportPosition = otherImports.find(module);
+      if (seenOtherImportPosition != otherImports.end()) {
+        for (auto *seenOtherImport : seenOtherImportPosition->getSecond())
+          diagnose(seenOtherImport, nextImport);
 
-      if (predicate(nextImport)) {
-        // We found a matching import.
-        bool isNew = matchingImports.insert({module, nextImport}).second;
-        if (!isNew)
-          continue;
+        // We're done with these; keep the map small if possible.
+        otherImports.erase(seenOtherImportPosition);
+      }
+      continue;
+    }
 
-        auto seenOtherImportPosition = otherImports.find(module);
-        if (seenOtherImportPosition != otherImports.end()) {
-          for (auto *seenOtherImport : seenOtherImportPosition->getSecond())
-            diagnose(seenOtherImport, nextImport);
+    // We saw a non-matching import. Is that in conflict with what we've seen?
+    if (auto *seenMatchingImport = matchingImports.lookup(module)) {
+      diagnose(nextImport, seenMatchingImport);
+      continue;
+    }
 
-          // We're done with these; keep the map small if possible.
-          otherImports.erase(seenOtherImportPosition);
-        }
-        continue;
-      }
+    // Otherwise, record it for later.
+    otherImports[module].push_back(nextImport);
+  }
+}
 
-      // We saw a non-matching import. Is that in conflict with what we've seen?
-      if (auto *seenMatchingImport = matchingImports.lookup(module)) {
-        diagnose(nextImport, seenMatchingImport);
-        continue;
-      }
+/// Finds all import declarations for a single module that inconsistently match
+/// \c predicate and passes each pair of inconsistent imports to \c diagnose.
+template <typename Pred, typename Diag>
+static void findInconsistentImportsAcrossModule(ModuleDecl *mod, Pred predicate,
+                                    Diag diagnose) {
+  llvm::DenseMap<ModuleDecl *, const ImportDecl *> matchingImports;
+  llvm::DenseMap<ModuleDecl *, std::vector<const ImportDecl *>> otherImports;
 
-      // Otherwise, record it for later.
-      otherImports[module].push_back(nextImport);
-    }
+  for (const FileUnit *file : mod->getFiles()) {
+    auto *SF = dyn_cast<SourceFile>(file);
+    if (!SF)
+      continue;
+
+    findInconsistentImportsAcrossFile(SF, predicate, diagnose,
+                                      matchingImports, otherImports);
   }
 }
 
@@ -830,7 +842,7 @@ CheckInconsistentImplementationOnlyImportsRequest::evaluate(
     return decl->getAttrs().hasAttribute<ImplementationOnlyAttr>();
   };
 
-  findInconsistentImports(mod, predicate, diagnose);
+  findInconsistentImportsAcrossModule(mod, predicate, diagnose);
   return {};
 }
 
@@ -855,7 +867,7 @@ CheckInconsistentWeakLinkedImportsRequest::evaluate(Evaluator &evaluator,
     return decl->getAttrs().hasAttribute<WeakLinkedAttr>();
   };
 
-  findInconsistentImports(mod, predicate, diagnose);
+  findInconsistentImportsAcrossModule(mod, predicate, diagnose);
   return {};
 }