From e95cb252be0187a46a1ee1809329b598d666053e Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gunnar@beutner.name>
Date: Mon, 12 Apr 2021 13:28:33 +0200
Subject: [PATCH] Toolchain: Install system headers before building GCC

GCC determines whether the system's <limits.h> header is usable
and installs a different version of its own <limits.h> header
depending on whether the system header file exists.

If the system header is missing GCC's <limits.h> header does not
include the system header via #include_next.

For this to work we need to install LibC's headers before
attempting to build GCC.

Also, re-running BuildIt.sh "hides" this problem because at that
point the sysroot directory also already has a <limits.h> header
file from the previous build.
---
 Toolchain/BuildIt.sh | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/Toolchain/BuildIt.sh b/Toolchain/BuildIt.sh
index c8f0cb5024..4f245a1ce0 100755
--- a/Toolchain/BuildIt.sh
+++ b/Toolchain/BuildIt.sh
@@ -239,15 +239,6 @@ pushd "$DIR/Build/$ARCH"
                                             --enable-lto \
                                             ${TRY_USE_LOCAL_TOOLCHAIN:+"--quiet"} || exit 1
 
-        echo "XXX build gcc and libgcc"
-        "$MAKE" -j "$MAKEJOBS" all-gcc || exit 1
-        if [ "$(uname -s)" = "OpenBSD" ]; then
-            ln -sf liblto_plugin.so.0.0 gcc/liblto_plugin.so
-        fi
-        "$MAKE" -j "$MAKEJOBS" all-target-libgcc || exit 1
-        echo "XXX install gcc and libgcc"
-        "$MAKE" install-gcc install-target-libgcc || exit 1
-
         echo "XXX serenity libc and libm headers"
         mkdir -p "$BUILD"
         pushd "$BUILD"
@@ -261,6 +252,15 @@ pushd "$DIR/Build/$ARCH"
             unset SRC_ROOT
         popd
 
+        echo "XXX build gcc and libgcc"
+        "$MAKE" -j "$MAKEJOBS" all-gcc || exit 1
+        if [ "$(uname -s)" = "OpenBSD" ]; then
+            ln -sf liblto_plugin.so.0.0 gcc/liblto_plugin.so
+        fi
+        "$MAKE" -j "$MAKEJOBS" all-target-libgcc || exit 1
+        echo "XXX install gcc and libgcc"
+        "$MAKE" install-gcc install-target-libgcc || exit 1
+
         echo "XXX build libstdc++"
         "$MAKE" -j "$MAKEJOBS" all-target-libstdc++-v3 || exit 1
         echo "XXX install libstdc++"