#!/bin/sh
set -eu
base="${TMPDIR-/tmp}/mcpu-cpp-sys-root-$$"
abs_root="$base/absolute-root"
rel_root="$base/relative-root"
home="$base/home"
mkdir -p "$abs_root/include/as" "$rel_root/include/as" \
         "$home/.mcpu/etc" "$base/forbidden"
trap 'rm -rf "$base"' EXIT HUP INT TERM

cat > "$abs_root/include/as/sys-root.h" <<'EOT'
int from_absolute_sys_root = 103;
EOT
cat > "$rel_root/include/as/sys-root.h" <<'EOT'
int from_relative_sys_root = 104;
EOT

cat > "$home/.mcpu/etc/mcpu-cpp.conf" <<EOT
MCPU_CPP_INCLUDE_PATH = $base/forbidden;
MCPU_CPP_SYSTEM_INCLUDE_PATH = $base/forbidden;
MCPU_CPP_SYS_ROOT_SENTINEL = user-config-must-not-be-read;
EOT

cat > "$base/explicit.conf" <<EOT
MCPU_CPP_SYSTEM_INCLUDE_PATH = $base/forbidden;
MCPU_CPP_SYS_ROOT_SENTINEL = explicit-config-must-not-be-read;
EOT

cat > "$base/main.c" <<'EOT'
#lang "as"
#include <sys-root.h>
#endlang
EOT

# An absolute --sys-root replaces the runtime root for the system include tree
# and implies --no-config, including for an explicitly named config file.
HOME="$home" "$MCPU_CPP" --sys-root="$abs_root" \
  --config-file "$base/explicit.conf" -dconfig > "$base/absolute.config"
grep "^MCPU_CPP_SYSTEM_INCLUDE_PATH = $abs_root/include;$" \
  "$base/absolute.config" >/dev/null
if grep 'MCPU_CPP_SYS_ROOT_SENTINEL\|forbidden' "$base/absolute.config" >/dev/null; then
  echo '--sys-root read a configuration file' >&2
  exit 1
fi

HOME="$home" "$MCPU_CPP" --sys-root="$abs_root" \
  "$base/main.c" -o "$base/absolute.out"
grep '^int from_absolute_sys_root = 103;$' "$base/absolute.out" >/dev/null

# A relative --sys-root is interpreted relative to the invocation working
# directory and becomes an absolute effective system include root.
(
  cd "$base"
  HOME="$home" "$MCPU_CPP" --sys-root=relative-root -dconfig \
    > "$base/relative.config"
  HOME="$home" "$MCPU_CPP" --sys-root=relative-root \
    "$base/main.c" -o "$base/relative.out"
)
grep "^MCPU_CPP_SYSTEM_INCLUDE_PATH = $rel_root/include;$" \
  "$base/relative.config" >/dev/null
grep '^int from_relative_sys_root = 104;$' "$base/relative.out" >/dev/null

# The separated spelling is accepted as the same option.
HOME="$home" "$MCPU_CPP" --sys-root "$abs_root" -dsearch-dirs \
  > "$base/separate.search"
grep "^search: $abs_root/include/as$" "$base/separate.search" >/dev/null
grep "^search: $abs_root/include$" "$base/separate.search" >/dev/null

# An empty system root is never accepted.
if HOME="$home" "$MCPU_CPP" --sys-root= -dconfig \
     > "$base/empty.out" 2> "$base/empty.err"; then
  echo 'empty --sys-root unexpectedly accepted' >&2
  exit 1
fi