From bcaa60cabe0255adf7f5ba58ca2adfa8c086f398 Mon Sep 17 00:00:00 2001
From: Anthony Printup <92564080+anthonyprintup@users.noreply.github.com>
Date: Mon, 12 Jun 2023 15:41:20 +0200
Subject: [PATCH] feat: Added SYSTEM flag support to fetch-content

---
 docs/cmake-toml.md         | 1 +
 include/project_parser.hpp | 1 +
 src/cmake_generator.cpp    | 6 +++++-
 src/project_parser.cpp     | 9 +++++++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/docs/cmake-toml.md b/docs/cmake-toml.md
index 593f1ed..00661ce 100644
--- a/docs/cmake-toml.md
+++ b/docs/cmake-toml.md
@@ -151,6 +151,7 @@ condition = "mycondition"
 git = "https://github.com/myuser/gitcontent"
 tag = "v0.1"
 shallow = false
+system = false
 
 [fetch-content.svncontent]
 condition = "mycondition"
diff --git a/include/project_parser.hpp b/include/project_parser.hpp
index 7b7a855..9c8842f 100644
--- a/include/project_parser.hpp
+++ b/include/project_parser.hpp
@@ -155,6 +155,7 @@ struct Content {
     Condition<std::string> cmake_after;
     ConditionVector include_before;
     ConditionVector include_after;
+    bool system;
 };
 
 enum MsvcRuntimeType {
diff --git a/src/cmake_generator.cpp b/src/cmake_generator.cpp
index 712a64a..a871d3d 100644
--- a/src/cmake_generator.cpp
+++ b/src/cmake_generator.cpp
@@ -917,7 +917,11 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 version_info = " (" + content.arguments.at("SVN_REVISION") + ")";
             }
             cmd("message")("STATUS", "Fetching " + content.name + version_info + "...");
-            cmd("FetchContent_Declare")(content.name, content.arguments);
+            if (content.system) {
+                cmd("FetchContent_Declare")(content.name, "SYSTEM", content.arguments);
+            } else {
+                cmd("FetchContent_Declare")(content.name, content.arguments);
+            }
             cmd("FetchContent_MakeAvailable")(content.name).endl();
 
             gen.conditional_includes(content.include_after);
diff --git a/src/project_parser.cpp b/src/project_parser.cpp
index 8c99b40..1fb571b 100644
--- a/src/project_parser.cpp
+++ b/src/project_parser.cpp
@@ -443,6 +443,15 @@ Project::Project(const Project *parent, const std::string &path, bool build) : p
             c.optional("cmake-after", content.cmake_after);
             c.optional("include-before", content.include_before);
             c.optional("include-after", content.include_after);
+            c.optional("system", content.system);
+
+            // Check if the minimum version requirement is satisfied (CMake 3.25)
+            if (c.contains("system") && !this->cmake_minimum_version(3, 25)) {
+                throw_key_error("The system argument is only supported on CMake version 3.25 and above.\nSet the CMake version in cmake.toml:\n"
+                                "[cmake]\n"
+                                "version = \"3.25\"\n",
+                                "system", "");
+            }
 
             for (const auto &argItr : itr.second.as_table()) {
                 std::string value;