From e2020d51324a7961ac6627acbe0730451e0e68e6 Mon Sep 17 00:00:00 2001
From: Michael Byrne <michael@michaelbyrne.io>
Date: Sat, 23 Oct 2021 19:50:22 +1100
Subject: [PATCH 1/4] Add documentation for sentinel-terminated slicing

---
 doc/langref.html.in | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/doc/langref.html.in b/doc/langref.html.in
index 9e5edee9f883..10f0a2cafa0d 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -2914,6 +2914,42 @@ test "null terminated slice" {
 
     try expect(slice.len == 5);
     try expect(slice[5] == 0);
+}
+      {#code_end#}
+      <p>
+      Sentinel-terminated slices can also be created using a variation of the slice syntax 
+      {#syntax#}data[start..end :x]{#endsyntax#}, where {#syntax#}data{#endsyntax#} is a many-item pointer, 
+      array or slice and {#syntax#}x{#endsyntax#} is the sentinel value.
+      </p>
+      {#code_begin|test|null_terminated_slicing#}
+const std = @import("std");
+const expect = std.testing.expect;
+
+test "null terminated slicing" {
+    var array = [_]u8{ 3, 2, 1, 0, 3, 2, 1, 0 };
+    var runtime_length: usize = 3;
+    const slice = array[0..runtime_length :0];
+
+    try expect(@TypeOf(slice) == [:0]u8);
+    try expect(slice.len == 3);
+}
+      {#code_end#}
+      <p>
+      Sentinel-terminated slicing assumes that the element in the sentinel position of the backing data is 
+      actually the sentinel value. If this is not the case a runtime error will result.
+      </p>
+      {#code_begin|exe_err|illegal_null_terminated_slicing#}
+pub fn main() void {
+    var array = [_]u8{ 3, 2, 1, 0 };
+
+    // Creating a sentinel-terminated slice from the array with a length of 2 
+    // will result in the value `1` occupying the sentinel element position. 
+    // This does not match the indicated sentinel value of `0` and will lead 
+    // to a runtime panic.
+    var runtime_length: usize = 2;
+    const slice = array[0..runtime_length :0];
+
+    _ = slice;
 }
       {#code_end#}
       {#see_also|Sentinel-Terminated Pointers|Sentinel-Terminated Arrays#}

From d5525b2d6183bcc1f42babcd068a3bd656eaff0c Mon Sep 17 00:00:00 2001
From: Michael Byrne <accounts@michaelbyrne.io>
Date: Thu, 28 Oct 2021 07:19:03 +1100
Subject: [PATCH 2/4] Change 'assumes' to 'asserts'

Co-authored-by: Andrew Kelley <andrew@ziglang.org>
---
 doc/langref.html.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/langref.html.in b/doc/langref.html.in
index 10f0a2cafa0d..5b25b0b50b09 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -2935,7 +2935,7 @@ test "null terminated slicing" {
 }
       {#code_end#}
       <p>
-      Sentinel-terminated slicing assumes that the element in the sentinel position of the backing data is 
+      Sentinel-terminated slicing asserts that the element in the sentinel position of the backing data is 
       actually the sentinel value. If this is not the case a runtime error will result.
       </p>
       {#code_begin|exe_err|illegal_null_terminated_slicing#}

From 06ded47dceaaa8a272c7a5f069bc313de068af77 Mon Sep 17 00:00:00 2001
From: Michael Byrne <accounts@michaelbyrne.io>
Date: Thu, 28 Oct 2021 07:19:58 +1100
Subject: [PATCH 3/4] Use more standard terminology for undefined behaviour

Co-authored-by: Andrew Kelley <andrew@ziglang.org>
---
 doc/langref.html.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/langref.html.in b/doc/langref.html.in
index 5b25b0b50b09..372b66b8e1f8 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -2936,7 +2936,7 @@ test "null terminated slicing" {
       {#code_end#}
       <p>
       Sentinel-terminated slicing asserts that the element in the sentinel position of the backing data is 
-      actually the sentinel value. If this is not the case a runtime error will result.
+      actually the sentinel value. If this is not the case, safety-protected {#link|Undefined Behavior#} results.
       </p>
       {#code_begin|exe_err|illegal_null_terminated_slicing#}
 pub fn main() void {

From e15c9e9e5d2563fa8a1bc5aac09f7d94eefe3a93 Mon Sep 17 00:00:00 2001
From: Michael Byrne <michael@michaelbyrne.io>
Date: Thu, 28 Oct 2021 07:40:11 +1100
Subject: [PATCH 4/4] Switch illegal slicing example to a test

---
 doc/langref.html.in | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/doc/langref.html.in b/doc/langref.html.in
index 372b66b8e1f8..5003e1b90739 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -2938,10 +2938,13 @@ test "null terminated slicing" {
       Sentinel-terminated slicing asserts that the element in the sentinel position of the backing data is 
       actually the sentinel value. If this is not the case, safety-protected {#link|Undefined Behavior#} results.
       </p>
-      {#code_begin|exe_err|illegal_null_terminated_slicing#}
-pub fn main() void {
-    var array = [_]u8{ 3, 2, 1, 0 };
+      {#code_begin|test_safety|sentinel mismatch#}
+const std = @import("std");
+const expect = std.testing.expect;
 
+test "sentinel mismatch" {
+    var array = [_]u8{ 3, 2, 1, 0 };
+    
     // Creating a sentinel-terminated slice from the array with a length of 2 
     // will result in the value `1` occupying the sentinel element position. 
     // This does not match the indicated sentinel value of `0` and will lead