CHECK-NEXT: fix edge case when on the first line without a match (fixes

#96)

filecheck/FileCheck.py

@@ -602,29 +602,32 @@ def main():
 
                 exit(1)
             else:
-                assert current_scan_base > 0
-                previous_matched_line = input_lines[current_scan_base - 1].rstrip()
-
                 print("{}:{}:{}: error: CHECK-NEXT: is not on the line after the previous match"
                       .format(check_file,
                               current_check.check_line_idx + 1,
                               current_check.start_index + 1))
                 print(current_check.source_line.rstrip())
                 print("^".rjust(current_check.start_index + 1))
 
-                matching_line = input_lines[matching_line_idx].rstrip()
-                print("<stdin>:{}:1: note: 'next' match was here".format(matching_line_idx + 1))
-                print(matching_line)
-                print("^")
-
-                print("<stdin>:{}:{}: note: previous match ended here".format(current_scan_base, len(previous_matched_line) + 1))
-                print(previous_matched_line)
-                print("^".rjust(len(previous_matched_line) + 1))
-                print("<stdin>:{}:{}: note: non-matching line after previous match is here".format(current_scan_base + 1, 1))
-                print(last_read_line)
-                print("^")
-
-                exit(1)
+                # It is very weird that exit code can be both 1 and 2 in the
+                # "CHECK-NEXT: is not on the line" scenario.
+                if current_scan_base > 0:
+                    matching_line = input_lines[matching_line_idx].rstrip()
+                    print("<stdin>:{}:1: note: 'next' match was here".format(matching_line_idx + 1))
+                    print(matching_line)
+                    print("^")
+
+                    previous_matched_line = input_lines[current_scan_base - 1].rstrip()
+                    print("<stdin>:{}:{}: note: previous match ended here".format(current_scan_base, len(previous_matched_line) + 1))
+                    print(previous_matched_line)
+                    print("^".rjust(len(previous_matched_line) + 1))
+                    print("<stdin>:{}:{}: note: non-matching line after previous match is here".format(current_scan_base + 1, 1))
+                    print(last_read_line)
+                    print("^")
+
+                    exit(1)
+                else:
+                    exit(2)
 
         raise NotImplementedError()
 

tests/integration/tests/check_commands/CHECK-NEXT/03-negative-match-check-next-on-the-first-line-no-match-exist/filecheck.check

@@ -0,0 +1 @@
+// CHECK-NEXT: 2

tests/integration/tests/check_commands/CHECK-NEXT/03-negative-match-check-next-on-the-first-line-no-match-exist/filecheck.input

@@ -0,0 +1,2 @@
+3
+[2]

tests/integration/tests/check_commands/CHECK-NEXT/03-negative-match-check-next-on-the-first-line-no-match-exist/sample.itest

@@ -0,0 +1,3 @@
+; RUN: cat %S/filecheck.input | (%FILECHECK_EXEC %S/filecheck.check; test $? = 2;) | %FILECHECK_TESTER_EXEC %s --strict-whitespace --match-full-lines
+; CHECK:{{^.*}}FileCheck{{(\.py)?$}}
+; CHECK-EMPTY