fix removal range of const kw

Author: 5chmidti

clang-tools-extra/clang-tidy/modernize/UseConstexprCheck.cpp

@@ -921,11 +921,16 @@ void UseConstexprCheck::onEndOfTranslationUnit() {
         << Var << R
         << FixItHint::CreateInsertion(Var->getInnerLocStart(),
                                       ConstexprString + " ");
+    // Since either of the locs can be in a macro, use `makeFileCharRange` to be
+    // sure that we have a consistent `CharSourceRange`, located entirely in the
+    // source file.
+    CharSourceRange FileRange = Lexer::makeFileCharRange(
+        CharSourceRange::getCharRange(Var->getInnerLocStart(),
+                                      Var->getLocation()),
+        Var->getASTContext().getSourceManager(), getLangOpts());
     if (const std::optional<Token> ConstToken =
             utils::lexer::getQualifyingToken(
-                tok::TokenKind::kw_const,
-                CharSourceRange::getTokenRange(Var->getSourceRange()),
-                Var->getASTContext(),
+                tok::TokenKind::kw_const, FileRange, Var->getASTContext(),
                 Var->getASTContext().getSourceManager())) {
       Diag << FixItHint::CreateRemoval(ConstToken->getLocation());
     }

clang-tools-extra/test/clang-tidy/checkers/modernize/use-constexpr.cpp

@@ -454,6 +454,10 @@ namespace variable {
 
             static auto e1 = TemplatedVar1<int> + TemplatedVar1<unsigned int>;
         }
+
+    const auto check = [](const int & ref) { };
+    // CHECK-MESSAGES-17: :[[@LINE-1]]:16: warning: variable 'check' can be declared 'constexpr' [modernize-use-constexpr]
+    // CHECK-FIXES-17: constexpr  auto check = [](const int & ref) { };
     } // namespace literal_type
 
     namespace struct_type {