AST: Simplify the interface of DiagnosticEngine::getBestAddImportFixItLoc().

For clarity, it should just take a `SourceFile`.

Author: tshortli

include/swift/AST/DiagnosticEngine.h

@@ -852,9 +852,6 @@ namespace swift {
 
     static const char *fixItStringFor(const FixItID id);
 
-    /// Get the best location where an 'import' fixit might be offered.
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member) const;
-
     /// Add a token-based replacement fix-it to the currently-active
     /// diagnostic.
     template <typename... ArgTypes>
@@ -1572,11 +1569,7 @@ namespace swift {
     SourceLoc getDefaultDiagnosticLoc() const {
       return bufferIndirectlyCausingDiagnostic;
     }
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member,
-                                       SourceFile *sourceFile) const;
-    SourceLoc getBestAddImportFixItLoc(const Decl *Member) const {
-      return getBestAddImportFixItLoc(Member, nullptr);
-    }
+    SourceLoc getBestAddImportFixItLoc(SourceFile *sf) const;
   };
 
   inline SourceManager &InFlightDiagnostic::getSourceManager() {

lib/AST/DiagnosticEngine.cpp

@@ -313,18 +313,12 @@ InFlightDiagnostic::fixItReplaceChars(SourceLoc Start, SourceLoc End,
   return *this;
 }
 
-SourceLoc
-DiagnosticEngine::getBestAddImportFixItLoc(const Decl *Member,
-                                           SourceFile *sourceFile) const {
+SourceLoc DiagnosticEngine::getBestAddImportFixItLoc(SourceFile *SF) const {
   auto &SM = SourceMgr;
 
   SourceLoc bestLoc;
-
-  auto SF =
-      sourceFile ? sourceFile : Member->getDeclContext()->getParentSourceFile();
-  if (!SF) {
+  if (!SF)
     return bestLoc;
-  }
 
   for (auto item : SF->getTopLevelItems()) {
     // If we found an import declaration, we want to insert after it.
@@ -356,19 +350,21 @@ DiagnosticEngine::getBestAddImportFixItLoc(const Decl *Member,
 
 InFlightDiagnostic &InFlightDiagnostic::fixItAddImport(StringRef ModuleName) {
   assert(IsActive && "Cannot modify an inactive diagnostic");
-  auto Member = Engine->ActiveDiagnostic->getDecl();
-  SourceLoc bestLoc = Engine->getBestAddImportFixItLoc(Member);
+  auto decl = Engine->ActiveDiagnostic->getDecl();
+  if (!decl)
+    return *this;
 
-  if (bestLoc.isValid()) {
-    llvm::SmallString<64> importText;
-    importText += "import ";
-    importText += ModuleName;
-    importText += "\n";
+  auto bestLoc = Engine->getBestAddImportFixItLoc(
+      decl->getDeclContext()->getOutermostParentSourceFile());
+  if (!bestLoc.isValid())
+    return *this;
 
-    return fixItInsert(bestLoc, importText);
-  }
+  llvm::SmallString<64> importText;
+  importText += "import ";
+  importText += ModuleName;
+  importText += "\n";
 
-  return *this;
+  return fixItInsert(bestLoc, importText);
 }
 
 InFlightDiagnostic &

lib/Sema/TypeCheckNameLookup.cpp

@@ -990,7 +990,7 @@ diagnoseAndFixMissingImportForMember(const ValueDecl *decl, SourceFile *sf,
   diagnoseMissingImportsForMember(decl, modulesToImport, sf, loc);
 
   auto &ctx = sf->getASTContext();
-  SourceLoc bestLoc = ctx.Diags.getBestAddImportFixItLoc(decl, sf);
+  SourceLoc bestLoc = ctx.Diags.getBestAddImportFixItLoc(sf);
   if (!bestLoc.isValid())
     return;