[PATCH] D82654: [libTooling] Improve error message from failure in selection Stencil

[Yitzhak Mandelbaum via Phabricator via cfe-commits]

ymandel created this revision.
ymandel added a reviewer: gribozavr2.
Herald added a project: clang.

This patch improves the error message provided by the stencil that handles
source from a range selector.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D82654

Files:
  clang/lib/Tooling/Transformer/Stencil.cpp


Index: clang/lib/Tooling/Transformer/Stencil.cpp
===================================================================
--- clang/lib/Tooling/Transformer/Stencil.cpp
+++ clang/lib/Tooling/Transformer/Stencil.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 #include <atomic>
 #include <memory>
 #include <string>
@@ -232,8 +233,31 @@
     return RawRange.takeError();
   CharSourceRange Range = Lexer::makeFileCharRange(
       *RawRange, *Match.SourceManager, Match.Context->getLangOpts());
+  if (Range.isInvalid()) {
+    // Validate the original range to attempt to get a meaningful error message.
+    // If it's valid, then something else is the cause and we just return the
+    // generic failure message.
+    if (auto Err = tooling::validateEditRange(*RawRange, *Match.SourceManager))
+      return handleErrors(std::move(Err), [](std::unique_ptr<StringError> E) {
+        assert(E->convertToErrorCode() ==
+                   llvm::make_error_code(errc::invalid_argument) &&
+               "Validation errors must be carry the invalid_argument code");
+        return llvm::createStringError(
+            errc::invalid_argument,
+            "selected range could not be resolved to a valid source range; " +
+                E->getMessage());
+      });
+    return llvm::createStringError(
+        errc::invalid_argument,
+        "selected range could not be resolved to a valid source range");
+  }
+  // Validate `Range`, because `makeFileCharRange` accepts some ranges that
+  // `validateEditRange` rejects.
   if (auto Err = tooling::validateEditRange(Range, *Match.SourceManager))
-    return Err;
+    return joinErrors(
+        llvm::createStringError(errc::invalid_argument,
+                                "selected range is not valid for editing"),
+        std::move(Err));
   *Result += tooling::getText(Range, *Match.Context);
   return Error::success();
 }


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