[llvm] [FileCheck] Clarify --implicit-check-not coverage in CommandGuide (PR #226476)

[Emil Laine via llvm-commits]

https://github.com/emillaine updated https://github.com/llvm/llvm-project/pull/226476

>From f62324bdfea1233110acd1401d01aab5ed08037d Mon Sep 17 00:00:00 2001
From: Emil Laine <laine.emil at gmail.com>
Date: Fri, 25 Sep 2026 15:58:15 +0300
Subject: [PATCH] [FileCheck] Clarify --implicit-check-not coverage in
 CommandGuide

The option description said checks apply "between positive checks",
which reads as gaps only. The pattern is actually rejected anywhere in
the input except text matched by a positive check: before the first
check, between checks, after the last check, and across the whole input
when there are no positive checks.
---
 llvm/docs/CommandGuide/FileCheck.md | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/docs/CommandGuide/FileCheck.md b/llvm/docs/CommandGuide/FileCheck.md
index 390cb0c77c6ed0..2ba3b0c209a878 100644
--- a/llvm/docs/CommandGuide/FileCheck.md
+++ b/llvm/docs/CommandGuide/FileCheck.md
@@ -97,9 +97,10 @@ FileCheck to use case-insensitive matching.
 :::
 
 :::{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.
+Adds implicit negative checks for the specified patterns across the whole
+input. A pattern occurrence fails the check unless a positive check matches
+that same text. 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