[clang] Enforce 1-based indexing for command line source locations (#139457)

Fixes #139375

Clang expects command line source locations to be provided using 1-based
indexing.
Currently, Clang does not reject zero as invalid argument for column or
line number, which can cause Clang to crash.

This commit extends validation in `ParsedSourceLocation::FromString` to
only accept (unsinged) non-zero integers.

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 3945129..fd48e42 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3112,9 +3112,11 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   if (const Arg *A = Args.getLastArg(OPT_code_completion_at)) {
     Opts.CodeCompletionAt =
       ParsedSourceLocation::FromString(A->getValue());
-    if (Opts.CodeCompletionAt.FileName.empty())
+    if (Opts.CodeCompletionAt.FileName.empty()) {
       Diags.Report(diag::err_drv_invalid_value)
-        << A->getAsString(Args) << A->getValue();
+          << A->getAsString(Args) << A->getValue();
+      Diags.Report(diag::note_command_line_code_loc_requirement);
+    }
   }
 
   Opts.Plugins = Args.getAllArgValues(OPT_load);