Set minimum deployment target for macOS builds (#8004)

Set minimum deployment target for macOS builds
- Calculates MACOSX_DEPLOYMENT_TARGET based on qmake's minos value
- Echo's Lowest SDK supported for information purposes
---------

Co-authored-by: Tres Finocchiaro <tres.finocchiaro@gmail.com>

.github/workflows/build.yml

@@ -235,6 +235,7 @@ jobs:
       - name: Configure
         run: |
           ccache --zero-stats
+          source .github/workflows/macos-env.sh
           mkdir build
           cmake -S . \
                 -B build \

.github/workflows/macos-env.sh

@@ -0,0 +1,121 @@
+#!/usr/bin/env bash
+# Calculate macOS-specific environment variables
+# 1. Sets the value of MACOSX_DEPLOYMENT_TARGET by matching another binary on the system.
+#
+# Usage:
+#    source macos-env.sh [package_manager] [package_name] [package_version]
+#
+# Example:
+#    source macos-env.sh brew qt 5
+#    source macos-env.sh port wget
+
+set -e
+
+unset package_manager package_name package_version
+
+# Obtain the package manager
+if [ -n "$1" ]; then
+	# Set package manager to first parameter
+	package_manager="$1"
+	case "$package_manager" in
+		"homebrew")
+			package_manager="brew"
+			;;
+		"macports")
+			package_manager="port"
+			;;
+	esac
+	# Test the command
+	if ! command -v "$package_manager" &> /dev/null; then
+    	echo "ERROR: Command '$package_manager' was not found, aborting." 1>&2
+    	exit 1
+    fi
+else
+	# Try to guess the package manager
+	if command -v brew &> /dev/null; then
+		package_manager="brew"
+	elif command -v port &> /dev/null; then
+		package_manager="port"
+	else
+		echo "WARNING: A compatible package manager wasn't found, we'll search for '$package_name' on \$PATH instead" 1>&2
+	fi
+fi
+
+# Obtain the package name
+if [ -n "$2" ]; then
+	package_name="$2"
+else
+	package_name="qt"
+fi
+
+# Special fallback handling for when package_name != binary_name, adjust as needed
+if [ "$package_name" = "qt" ]; then
+	binary_name="qmake"
+elif [ "$package_name" = "fltk" ]; then
+	binary_name="fluid"
+else
+	# Assume the binary_name is the package_name
+	binary_name="$package_name"
+fi
+
+# Obtain the package version
+if [ -n "$3" ]; then
+	package_version="$3"
+else
+	if [ "$package_name" = "qt" ]; then
+		# Sane fallback for qt, adjust as needed
+      	package_version="5"
+    fi
+fi
+
+# Format $package_name to include $package_version
+if [ -n "$package_version" ]; then
+	# Specify qt version in package name
+	case "$package_manager" in
+        "port")
+        	case "$package_name" in
+                "qt")
+                	# Special handling for "qt5-qtbase"
+                	package_name="$package_name${package_version}-${package_name}base"
+                ;;
+            	*)
+            		package_name="$package_name$package_version"
+            	;;
+            esac
+            ;;
+        "brew" | *)
+            package_name="$package_name@$package_version"
+            ;;
+    esac
+fi
+
+# Determine MACOSX_DEPLOYMENT_TARGET
+if [ -n "$package_manager" ]; then
+	# Specify qt version in package name
+    	case "$package_manager" in
+            "port")
+				binary_path="$(port contents "$package_name" |grep "bin/${binary_name}\$" |head -1 |sed -e 's/^[[:space:]]*//')"
+                ;;
+            "brew" | *)
+            	binary_path="$("$package_manager" --prefix "$package_name")/bin/$binary_name"
+                ;;
+        esac
+        otool_out="$(otool -l "$binary_path")"
+
+else
+	otool_out="$(otool -l "$(which "$binary_name")")"
+fi
+
+echo "Using '$binary_name' (from $package_manager) to calculate the macOS deployment target..."
+
+min_ver="$(echo "$otool_out" |grep "minos" || echo "$otool_out" |grep -A 2 "LC_VERSION_MIN_MACOS"|grep "version")"
+MACOSX_DEPLOYMENT_TARGET="$(echo "$min_ver"|awk '{print $2}')"
+
+# Echo the lowest target macOS version supported by this SDK
+sdk_settings="$(xcrun --sdk macosx --show-sdk-path)/SDKSettings.plist"
+sdk_min="$(plutil -extract SupportedTargets.macosx.MinimumDeploymentTarget raw "$sdk_settings")"
+echo "- Lowest SDK supported by this environment is '$sdk_min' based on $sdk_settings"
+
+# Echo the sane target macOS version based on another build dependency
+export MACOSX_DEPLOYMENT_TARGET
+echo "- Exporting 'MACOSX_DEPLOYMENT_TARGET=$MACOSX_DEPLOYMENT_TARGET' based on $binary_name"