From 84290ed7c8f1f8d2695e6aa7d5f1aa3587e86412 Mon Sep 17 00:00:00 2001
From: martinfalisse <martinmotteditfalisse@gmail.com>
Date: Mon, 26 Sep 2022 14:04:05 +0200
Subject: [PATCH] Base+LibWeb: Make sure grid positions don't cause out of
 bounds

Add some tests to the test page to make sure that different combinations
of GridTrackPlacement don't cause out of bounds issues.
---
 Base/res/html/misc/display-grid.html                | 13 ++++++++-----
 .../LibWeb/Layout/GridFormattingContext.cpp         |  6 ++++++
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/Base/res/html/misc/display-grid.html b/Base/res/html/misc/display-grid.html
index eb7a33af17..fcf9c9d116 100644
--- a/Base/res/html/misc/display-grid.html
+++ b/Base/res/html/misc/display-grid.html
@@ -46,15 +46,18 @@
   <div class="grid-item" style="grid-row: span 2 / 1; grid-column: span 2 / 1;">1</div>
   <div class="grid-item" style="grid-row: span 2 / 1;">2</div>
   <div class="grid-item" style="grid-column: span 2 / 1;">3</div>
+  <div class="grid-item" style="grid-column-end: 1; grid-row-end: 1;">6</div>
 </div>
 
-<!-- 0 positioned grid items -->
+<!-- 0 positioned grid items and similar inputs -->
 <p>If you can see this message then the test passed.</p>
 <div class="grid-container">
-  <div class="grid-item" style="grid-row-end: 0;">1</div>
-  <div class="grid-item" style="grid-row: 0 / 0;">2</div>
-  <div class="grid-item" style="grid-column: 0 / 1;">3</div>
-  <div class="grid-item" style="grid-row: 1 / 0;">4</div>
+  <div class="grid-item" style="grid-row-end: 0;">2</div>
+  <div class="grid-item" style="grid-row: 0 / 0;">3</div>
+  <div class="grid-item" style="grid-column: 0 / 1;">4</div>
+  <div class="grid-item" style="grid-row: 1 / 0;">5</div>
+  <div class="grid-item" style="grid-row-end: 1;">1</div>
+  <div class="grid-item" style="grid-column-end: 1;">6</div>
 </div>
 
 <!-- Different column sizes -->
diff --git a/Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp
index 7b607cd0fd..f41e0ecf5c 100644
--- a/Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp
@@ -251,6 +251,9 @@ void GridFormattingContext::run(Box const& box, LayoutMode, AvailableSpace const
             if (row_start != row_end)
                 row_span = row_end - row_start;
         }
+        // FIXME: Have yet to find the spec for this.
+        if (!child_box.computed_values().grid_row_start().is_position() && child_box.computed_values().grid_row_end().is_position() && row_end == 1)
+            row_start = 1;
 
         // If the placement contains two spans, remove the one contributed by the end grid-placement
         // property.
@@ -361,6 +364,9 @@ void GridFormattingContext::run(Box const& box, LayoutMode, AvailableSpace const
                 if (column_start < 0)
                     column_start = 1;
             }
+            // FIXME: Have yet to find the spec for this.
+            if (!child_box.computed_values().grid_column_start().is_position() && child_box.computed_values().grid_column_end().is_position() && column_end == 1)
+                column_start = 1;
 
             // If a name is given as a <custom-ident>, only lines with that name are counted. If not enough
             // lines with that name exist, all implicit grid lines on the side of the explicit grid