clang-rename: improve error message when -old-name is used and could not find symbol

[vmiklos]

Summary

Old output was:

clang-rename: could not find symbol at tools/clang/tools/extra/test/clang-rename/ClassFindByName.cpp:1:1 (offset 0).

[omtcyfz]

clang-rename/USRFindingAction.cpp

168

I am not sure whether "could not find symbol called" would be a better wording. It doesn't sound good to me either. Probably something like "could not find symbol OldName" would be reasonable, too.

[vmiklos]

Probably something like "could not find symbol OldName" would be reasonable, too.

OK, changed.

[omtcyfz]

In D24002#528556, @vmiklos wrote:

Probably something like "could not find symbol OldName" would be reasonable, too.

OK, changed.

Great! Good catch, thank you!

The old wording should be confusing for most of the users.

clang-rename/USRFindingAction.cpp

if (!Point.isValid())
       return;
     const NamedDecl *FoundDecl = nullptr;
     if (OldName.empty()) {
       FoundDecl = getNamedDeclAt(Context, Point);
     } else {
       FoundDecl = getNamedDeclFor(Context, OldName);
     }
     if (FoundDecl == nullptr) {
+      if (OldName.empty()) {
         FullSourceLoc FullLoc(Point, SourceMgr);
         errs() << "clang-rename: could not find symbol at "
                << SourceMgr.getFilename(Point) << ":"
                << FullLoc.getSpellingLineNumber() << ":"
-             << FullLoc.getSpellingColumnNumber() << " (offset " << SymbolOffset
-             << ").\n";
+               << FullLoc.getSpellingColumnNumber() << " (offset "
+               << SymbolOffset << ").\n";
+      } else
+        errs() << "clang-rename: could not find symbol named " << OldName
+               << ".\n";
       return;
     }
 
     // If FoundDecl is a constructor or destructor, we want to instead take the
     // Decl of the corresponding class.
     if (const auto *CtorDecl = dyn_cast<CXXConstructorDecl>(FoundDecl)) {
       FoundDecl = CtorDecl->getParent();
     } else if (const auto *DtorDecl = dyn_cast<CXXDestructorDecl>(FoundDecl)) {

test/clang-rename/InvalidOldName.cpp

+// RUN: not clang-rename rename-all -new-name=Foo -old-name=Bar %s -- 2>&1 | FileCheck %s
+// CHECK: clang-rename: could not find symbol named Bar.