FileCheck: dump command line context with empty input

Differential Revision: http://reviews.llvm.org/D20716

llvm-svn: 271047

Author: david-xl

llvm/test/FileCheck/check-empty.txt

@@ -7,5 +7,6 @@
 ; NOFOO-NOT: foo
 
 ; EMPTY-ERR: FileCheck error: '-' is empty.
+; EMPTY-ERR-NEXT: FileCheck command line: {{.*}}FileCheck -check-prefix={{.*}}FOO {{.*}}check-empty.txt
 ; NO-EMPTY-ERR-NOT: FileCheck error: '-' is empty.
 ; NOT-FOUND: error: expected string not found in input

llvm/utils/FileCheck/FileCheck.cpp

@@ -1298,6 +1298,13 @@ static void AddCheckPrefixIfNeeded() {
     CheckPrefixes.push_back("CHECK");
 }
 
+static void DumpCommandLine(int argc, char **argv) {
+  errs() << "FileCheck command line: ";
+  for (int I = 0; I < argc; I++)
+    errs() << " " << argv[I];
+  errs() << "\n";
+}
+
 int main(int argc, char **argv) {
   sys::PrintStackTraceOnErrorSignal();
   PrettyStackTraceProgram X(argc, argv);
@@ -1331,6 +1338,7 @@ int main(int argc, char **argv) {
 
   if (File->getBufferSize() == 0 && !AllowEmptyInput) {
     errs() << "FileCheck error: '" << InputFilename << "' is empty.\n";
+    DumpCommandLine(argc, argv);
     return 2;
   }