From 08579bb971afdafa11031926ecdd1502e33851bc Mon Sep 17 00:00:00 2001
From: bruvzg <7645683+bruvzg@users.noreply.github.com>
Date: Wed, 8 Jun 2022 13:31:02 +0300
Subject: [PATCH] Fix FreeType crashing in GCC + LTO builds.

---
 thirdparty/README.md                          |  5 +++
 .../freetype/patches/fix_gcc_lto_build.diff   | 34 +++++++++++++++++++
 thirdparty/freetype/src/smooth/ftgrays.c      |  9 +++++
 3 files changed, 48 insertions(+)
 create mode 100644 thirdparty/freetype/patches/fix_gcc_lto_build.diff

diff --git a/thirdparty/README.md b/thirdparty/README.md
index 23a2ec77d9a..28c3e42ee89 100644
--- a/thirdparty/README.md
+++ b/thirdparty/README.md
@@ -141,6 +141,11 @@ Files extracted from upstream source:
 - `include/` folder, minus the `dlg` subfolder
 - `LICENSE.TXT` and `docs/FTL.TXT`
 
+Some changes have been made in order to prevent LTO from removing code.
+They are marked with `// -- GODOT start --` and `// -- GODOT end --`
+comments. Apply the patches in the `patches/` folder when syncing on newer upstream
+commits.
+
 
 ## glad
 
diff --git a/thirdparty/freetype/patches/fix_gcc_lto_build.diff b/thirdparty/freetype/patches/fix_gcc_lto_build.diff
new file mode 100644
index 00000000000..3c22b464c26
--- /dev/null
+++ b/thirdparty/freetype/patches/fix_gcc_lto_build.diff
@@ -0,0 +1,34 @@
+diff --git a/thirdparty/freetype/src/smooth/ftgrays.c b/thirdparty/freetype/src/smooth/ftgrays.c
+index 622035aa79..5d9e1600b7 100644
+--- a/thirdparty/freetype/src/smooth/ftgrays.c
++++ b/thirdparty/freetype/src/smooth/ftgrays.c
+@@ -1907,6 +1907,9 @@ typedef ptrdiff_t  FT_PtrDist;
+     0                                        /* delta    */
+   )
+ 
++// -- GODOT start --
++  static volatile int _lto_dummy = 0;
++// -- GODOT end --
+ 
+   static int
+   gray_convert_glyph_inner( RAS_ARG,
+@@ -1928,6 +1931,9 @@ typedef ptrdiff_t  FT_PtrDist;
+                   ras.max_ey,
+                   ras.cell_null - ras.cell_free,
+                   ras.cell_null - ras.cell_free == 1 ? "" : "s" ));
++// -- GODOT start --
++      _lto_dummy = error; // Prevents LTO from removing this branch.
++// -- GODOT end --
+     }
+     else
+     {
+@@ -1935,6 +1941,9 @@ typedef ptrdiff_t  FT_PtrDist;
+ 
+       FT_TRACE7(( "band [%d..%d]: to be bisected\n",
+                   ras.min_ey, ras.max_ey ));
++// -- GODOT start --
++      _lto_dummy = error; // Prevents LTO from removing this branch.
++// -- GODOT end --
+     }
+ 
+     return error;
diff --git a/thirdparty/freetype/src/smooth/ftgrays.c b/thirdparty/freetype/src/smooth/ftgrays.c
index 622035aa797..5d9e1600b7d 100644
--- a/thirdparty/freetype/src/smooth/ftgrays.c
+++ b/thirdparty/freetype/src/smooth/ftgrays.c
@@ -1907,6 +1907,9 @@ typedef ptrdiff_t  FT_PtrDist;
     0                                        /* delta    */
   )
 
+// -- GODOT start --
+  static volatile int _lto_dummy = 0;
+// -- GODOT end --
 
   static int
   gray_convert_glyph_inner( RAS_ARG,
@@ -1928,6 +1931,9 @@ typedef ptrdiff_t  FT_PtrDist;
                   ras.max_ey,
                   ras.cell_null - ras.cell_free,
                   ras.cell_null - ras.cell_free == 1 ? "" : "s" ));
+// -- GODOT start --
+      _lto_dummy = error; // Prevents LTO from removing this branch.
+// -- GODOT end --
     }
     else
     {
@@ -1935,6 +1941,9 @@ typedef ptrdiff_t  FT_PtrDist;
 
       FT_TRACE7(( "band [%d..%d]: to be bisected\n",
                   ras.min_ey, ras.max_ey ));
+// -- GODOT start --
+      _lto_dummy = error; // Prevents LTO from removing this branch.
+// -- GODOT end --
     }
 
     return error;