Add FileCheck -implicit-check-not option to allow stricter tests without adding too many CHECK-NOTs manually.

Summary:
Add FileCheck -implicit-check-not option which allows specifying a
pattern that should only occur in the input when explicitly matched by a
positive check. This feature allows checking tool diagnostics in a way
clang -verify does it for compiler diagnostics.

The option has been tested on a number of clang-tidy checks, I'll post a link to
the clang-tidy patch to this thread.

Once there's an agreement on the general direction, I can add tests and
documentation.

Reviewers: djasper, bkramer

Reviewed By: bkramer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4462

llvm-svn: 212810

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/docs/CommandGuide/FileCheck.rst b/llvm/docs/CommandGuide/FileCheck.rst
index 5a60d60ae3d..5c60b2ad08b 100644
--- a/llvm/docs/CommandGuide/FileCheck.rst
+++ b/llvm/docs/CommandGuide/FileCheck.rst
@@ -49,6 +49,17 @@ OPTIONS
  The :option:`--strict-whitespace` argument disables this behavior. End-of-line
  sequences are canonicalized to UNIX-style ``\n`` in all modes.
 
+.. option:: --implicit-check-not check-pattern
+
+  Adds implicit negative checks for the specified patterns between positive
+  checks. The option allows writing stricter tests without stuffing them with
+  ``CHECK-NOT``s.
+
+  For example, "``--implicit-check-not warning:``" can be useful when testing
+  diagnostic messages from tools that don't have an option similar to ``clang
+  -verify``. With this option FileCheck will verify that input does not contain
+  warnings not covered by any ``CHECK:`` patterns.
+
 .. option:: -version
 
  Show the version number of this program.