From 67c4e4081cb6027122d02dabab4171298c2bd4e5 Mon Sep 17 00:00:00 2001
From: Mike Gelfand <mikedld@users.noreply.github.com>
Date: Fri, 16 Dec 2022 14:38:30 -0800
Subject: [PATCH] Add `ENABLE_WERROR` option for use on CI (#4381)

Defaults to `OFF`. Downstream packagers are advised against enabling it
as we can't guarantee it working on every possible configuration.

Added the actual compile flag in the GTK client subdirectory and not
the top-level CMakeLists.txt file due to other subprojects not being
ready.

Fixed the only GTK client warning reported by Clang on Mac.
---
 .github/workflows/actions.yml | 6 ++++++
 CMakeLists.txt                | 1 +
 gtk/CMakeLists.txt            | 3 +++
 gtk/PathButton.cc             | 6 +++---
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/actions.yml b/.github/workflows/actions.yml
index 1c5de1a14..10f5c09ae 100644
--- a/.github/workflows/actions.yml
+++ b/.github/workflows/actions.yml
@@ -210,6 +210,7 @@ jobs:
             -DENABLE_TESTS=OFF \
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_WEB=OFF \
+            -DENABLE_WERROR=ON \
             -DRUN_CLANG_TIDY=OFF
       - name: Make
         run: cmake --build obj --config RelWithDebInfo
@@ -284,6 +285,7 @@ jobs:
             -DENABLE_TESTS=OFF \
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_WEB=OFF \
+            -DENABLE_WERROR=ON \
             -DRUN_CLANG_TIDY=OFF
       - name: Make
         run: cmake --build obj --config RelWithDebInfo
@@ -375,6 +377,7 @@ jobs:
             -DENABLE_TESTS=ON `
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-dist == 'true' || needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} `
             -DENABLE_WEB=OFF `
+            -DENABLE_WERROR=ON `
             -DRUN_CLANG_TIDY=OFF
       - name: Make
         run: |
@@ -478,6 +481,7 @@ jobs:
             -DENABLE_TESTS=${{ (needs.what-to-make.outputs.make-tests == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_WEB=OFF \
+            -DENABLE_WERROR=ON \
             -DRUN_CLANG_TIDY=OFF
       - name: Make
         run: cmake --build obj --config RelWithDebInfo
@@ -553,6 +557,7 @@ jobs:
             -DENABLE_TESTS=${{ (needs.what-to-make.outputs.make-tests == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_WEB=OFF \
+            -DENABLE_WERROR=ON \
             -DRUN_CLANG_TIDY=OFF
       - name: Build
         run: cmake --build obj --config RelWithDebInfo
@@ -625,6 +630,7 @@ jobs:
             -DENABLE_TESTS=${{ (needs.what-to-make.outputs.make-tests == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_UTILS=${{ (needs.what-to-make.outputs.make-utils == 'true') && 'ON' || 'OFF' }} \
             -DENABLE_WEB=OFF \
+            -DENABLE_WERROR=ON \
             -DRUN_CLANG_TIDY=OFF
       - name: Build
         run: cmake --build obj --config RelWithDebInfo
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0267368e3..1bee0603b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -50,6 +50,7 @@ tr_auto_option(ENABLE_MAC           "Build Mac client" AUTO)
         option(ENABLE_TESTS         "Build unit tests" ON)
         option(ENABLE_LIGHTWEIGHT   "Optimize libtransmission for low-resource systems: smaller cache size, prefer unencrypted peer connections, etc." OFF)
         option(ENABLE_UTP           "Build µTP support" ON)
+        option(ENABLE_WERROR        "Treat warnings as errors" OFF)
         option(ENABLE_NLS           "Enable native language support" ON)
         option(INSTALL_DOC          "Build/install documentation" ON)
         option(INSTALL_LIB          "Install the library" OFF)
diff --git a/gtk/CMakeLists.txt b/gtk/CMakeLists.txt
index 634c05a9c..b8c57881f 100644
--- a/gtk/CMakeLists.txt
+++ b/gtk/CMakeLists.txt
@@ -1,6 +1,9 @@
 project(trgtk)
 
 add_compile_options(${C_WARNING_FLAGS})
+if(ENABLE_WERROR)
+    add_compile_options($<IF:$<CXX_COMPILER_ID:MSVC>,/WX,-Werror>)
+endif()
 
 execute_process(
     COMMAND
diff --git a/gtk/PathButton.cc b/gtk/PathButton.cc
index c2005e845..7c7e6d6df 100644
--- a/gtk/PathButton.cc
+++ b/gtk/PathButton.cc
@@ -41,9 +41,9 @@ private:
 #endif
 
 private:
+#if GTKMM_CHECK_VERSION(4, 0, 0)
     PathButton& widget_;
 
-#if GTKMM_CHECK_VERSION(4, 0, 0)
     Glib::Property<Gtk::FileChooser::Action> action_;
     Glib::Property<Glib::ustring> title_;
 
@@ -59,9 +59,9 @@ private:
 #endif
 };
 
-PathButton::Impl::Impl(PathButton& widget)
-    : widget_(widget)
+PathButton::Impl::Impl([[maybe_unused]] PathButton& widget)
 #if GTKMM_CHECK_VERSION(4, 0, 0)
+    : widget_(widget)
     , action_(widget, "action", Gtk::FileChooser::Action::OPEN)
     , title_(widget, "title", {})
     , image_(Gtk::make_managed<Gtk::Image>())