Meta: Move compiler detection functions to their own file

This way we can use them in other scripts that want to build Lagom
and pick a suitable host compiler.

Meta/find_compiler.sh

@@ -0,0 +1,78 @@
+# shellcheck shell=bash
+
+HOST_COMPILER=""
+
+is_supported_compiler() {
+    local COMPILER="$1"
+    if [ -z "$COMPILER" ]; then
+        return 1
+    fi
+
+    local VERSION=""
+    VERSION="$($COMPILER -dumpversion)" || return 1
+    local MAJOR_VERSION=""
+    MAJOR_VERSION="${VERSION%%.*}"
+    if $COMPILER --version 2>&1 | grep "Apple clang" >/dev/null; then
+        # Apple Clang version check
+        BUILD_VERSION=$(echo | $COMPILER -dM -E - | grep __apple_build_version__ | cut -d ' ' -f3)
+        # Xcode 14.3, based on upstream LLVM 15
+        [ "$BUILD_VERSION" -ge 14030022 ] && return 0
+    elif $COMPILER --version 2>&1 | grep "clang" >/dev/null; then
+        # Clang version check
+        [ "$MAJOR_VERSION" -ge 15 ] && return 0
+    else
+        # GCC version check
+        [ "$MAJOR_VERSION" -ge 12 ] && return 0
+    fi
+    return 1
+}
+
+find_newest_compiler() {
+    local BEST_VERSION=0
+    local BEST_CANDIDATE=""
+    for CANDIDATE in "$@"; do
+        if ! command -v "$CANDIDATE" >/dev/null 2>&1; then
+            continue
+        fi
+        if ! $CANDIDATE -dumpversion >/dev/null 2>&1; then
+            continue
+        fi
+        local VERSION=""
+        VERSION="$($CANDIDATE -dumpversion)"
+        local MAJOR_VERSION="${VERSION%%.*}"
+        if [ "$MAJOR_VERSION" -gt "$BEST_VERSION" ]; then
+            BEST_VERSION=$MAJOR_VERSION
+            BEST_CANDIDATE="$CANDIDATE"
+        fi
+    done
+    HOST_COMPILER=$BEST_CANDIDATE
+}
+
+pick_host_compiler() {
+    CC=${CC:-"cc"}
+    CXX=${CXX:-"cxx"}
+
+    if is_supported_compiler "$CC" && is_supported_compiler "$CXX"; then
+        return
+    fi
+
+    find_newest_compiler clang clang-15 clang-16 /opt/homebrew/opt/llvm/bin/clang
+    if is_supported_compiler "$HOST_COMPILER"; then
+        export CC="${HOST_COMPILER}"
+        export CXX="${HOST_COMPILER/clang/clang++}"
+        return
+    fi
+
+    find_newest_compiler egcc gcc gcc-12 gcc-13 /usr/local/bin/gcc-{12,13} /opt/homebrew/bin/gcc-{12,13}
+    if is_supported_compiler "$HOST_COMPILER"; then
+        export CC="${HOST_COMPILER}"
+        export CXX="${HOST_COMPILER/gcc/g++}"
+        return
+    fi
+
+    if [ "$(uname -s)" = "Darwin" ]; then
+        die "Please make sure that Xcode 14.3, Homebrew Clang 15, or higher is installed."
+    else
+        die "Please make sure that GCC version 12, Clang version 15, or higher is installed."
+    fi
+}

Meta/serenity.sh

@@ -86,6 +86,9 @@ DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 exit_if_running_as_root "Do not run serenity.sh as root, your Build directory will become root-owned"
 
+# shellcheck source=/dev/null
+. "${DIR}/find_compiler.sh"
+
 if [ -n "$1" ]; then
     TARGET="$1"; shift
 else
@@ -93,7 +96,6 @@ else
 fi
 
 CMAKE_ARGS=()
-HOST_COMPILER=""
 
 # Toolchain selection only applies to non-lagom targets.
 if [ "$TARGET" != "lagom" ] && [ -n "$1" ]; then
@@ -153,78 +155,6 @@ create_build_dir() {
     fi
 }
 
-is_supported_compiler() {
-    local COMPILER="$1"
-    if [ -z "$COMPILER" ]; then
-        return 1
-    fi
-
-    local VERSION=""
-    VERSION="$($COMPILER -dumpversion)" || return 1
-    local MAJOR_VERSION=""
-    MAJOR_VERSION="${VERSION%%.*}"
-    if $COMPILER --version 2>&1 | grep "Apple clang" >/dev/null; then
-        # Apple Clang version check
-        BUILD_VERSION=$(echo | $COMPILER -dM -E - | grep __apple_build_version__ | cut -d ' ' -f3)
-        # Xcode 14.3, based on upstream LLVM 15
-        [ "$BUILD_VERSION" -ge 14030022 ] && return 0
-    elif $COMPILER --version 2>&1 | grep "clang" >/dev/null; then
-        # Clang version check
-        [ "$MAJOR_VERSION" -ge 15 ] && return 0
-    else
-        # GCC version check
-        [ "$MAJOR_VERSION" -ge 12 ] && return 0
-    fi
-    return 1
-}
-
-find_newest_compiler() {
-    local BEST_VERSION=0
-    local BEST_CANDIDATE=""
-    for CANDIDATE in "$@"; do
-        if ! command -v "$CANDIDATE" >/dev/null 2>&1; then
-            continue
-        fi
-        if ! $CANDIDATE -dumpversion >/dev/null 2>&1; then
-            continue
-        fi
-        local VERSION=""
-        VERSION="$($CANDIDATE -dumpversion)"
-        local MAJOR_VERSION="${VERSION%%.*}"
-        if [ "$MAJOR_VERSION" -gt "$BEST_VERSION" ]; then
-            BEST_VERSION=$MAJOR_VERSION
-            BEST_CANDIDATE="$CANDIDATE"
-        fi
-    done
-    HOST_COMPILER=$BEST_CANDIDATE
-}
-
-pick_host_compiler() {
-    if is_supported_compiler "$CC" && is_supported_compiler "$CXX"; then
-        return
-    fi
-
-    find_newest_compiler clang clang-15 clang-16 /opt/homebrew/opt/llvm/bin/clang
-    if is_supported_compiler "$HOST_COMPILER"; then
-        export CC="${HOST_COMPILER}"
-        export CXX="${HOST_COMPILER/clang/clang++}"
-        return
-    fi
-
-    find_newest_compiler egcc gcc gcc-12 gcc-13 /usr/local/bin/gcc-{12,13} /opt/homebrew/bin/gcc-{12,13}
-    if is_supported_compiler "$HOST_COMPILER"; then
-        export CC="${HOST_COMPILER}"
-        export CXX="${HOST_COMPILER/gcc/g++}"
-        return
-    fi
-
-    if [ "$(uname -s)" = "Darwin" ]; then
-        die "Please make sure that Xcode 14.3, Homebrew Clang 15, or higher is installed."
-    else
-        die "Please make sure that GCC version 12, Clang version 15, or higher is installed."
-    fi
-}
-
 cmd_with_target() {
     is_valid_target || ( >&2 echo "Unknown target: $TARGET"; usage )