Add a comment for --vs-diagnostics.

llvm-svn: 367650

1 files changed, 21 insertions, 0 deletions

diff --git a/lld/Common/ErrorHandler.cpp b/lld/Common/ErrorHandler.cpp
index 592b5b508da..f22de2531f9 100644
--- a/lld/Common/ErrorHandler.cpp
+++ b/lld/Common/ErrorHandler.cpp
@@ -85,6 +85,27 @@ void lld::checkError(Error e) {
                   [&](ErrorInfoBase &eib) { error(eib.message()); });
 }
 
+// This is for --vs-diagnostics.
+//
+// Normally, lld's error message starts with argv[0]. Therefore, it usually
+// looks like this:
+//
+//   ld.lld: error: ...
+//
+// This error message style is unfortunately unfriendly to Visual Studio
+// IDE. VS interprets the first word of the first line as an error location
+// and make it clickable, thus "ld.lld" in the above message would become a
+// clickable text. When you click it, VS opens "ld.lld" executable file with
+// a binary editor.
+//
+// As a workaround, we print out an error location instead of "ld.lld" if
+// lld is running in VS diagnostics mode. As a result, error message will
+// look like this:
+//
+//   src/foo.c(35): error: ...
+//
+// This function returns an error location string. An error location is
+// extracted from an error message using regexps.
 std::string ErrorHandler::getLocation(const Twine &msg) {
   if (!vsDiagnostics)
     return logName;