Fix compilation warnings and re-enable werror=yes on Travis

Fix -Wunused-variable, -Wunused-but-set-variable and -Wswitch warnings
raised by GCC 8 and 9.

Fix -Wunused-function, -Wunused-private-field and
-Wtautological-constant-out-of-range-compare raised by Clang.

Fix MSVC 2019 warning C4804 (unsafe use of type 'bool' in comparison
operation).

GCC -Wcpp warnings/Clang -W#warnings (`#warning`) are no longer raising
errors and will thus not abort compilation with `werror=yes`.

Treat glslang headers are system headers to avoid raising warnings.

Re-enables us to build with `werror=yes` on Linux and macOS, thus
catching warnings that would be introduced by new code.

Fixes #36132.

4 files changed, 2 insertions, 50 deletions

diff --git a/scene/3d/soft_body.cpp b/scene/3d/soft_body.cpp
index 1c20677f64..c297bd2c80 100644
--- a/scene/3d/soft_body.cpp
+++ b/scene/3d/soft_body.cpp
@@ -561,7 +561,6 @@ const NodePath &SoftBody::get_parent_collision_ignore() const {
 
 void SoftBody::set_pinned_points_indices(Vector<SoftBody::PinnedPoint> p_pinned_points_indices) {
 	pinned_points = p_pinned_points_indices;
-	const PinnedPoint *w = pinned_points.ptr();
 	for (int i = pinned_points.size() - 1; 0 <= i; --i) {
 		pin_point(p_pinned_points_indices[i].point_index, true);
 	}
diff --git a/scene/3d/voxelizer.h b/scene/3d/voxelizer.h
index 0ea613e2fd..1d50f1cd18 100644
--- a/scene/3d/voxelizer.h
+++ b/scene/3d/voxelizer.h
@@ -109,7 +109,6 @@ private:
 	int color_scan_cell_width;
 	int bake_texture_size;
 	float cell_size;
-	float propagation;
 
 	int max_original_cells;
 	int leaf_voxel_count;
diff --git a/scene/main/scene_tree.cpp b/scene/main/scene_tree.cpp
index 818ae93d95..2a0825252d 100644
--- a/scene/main/scene_tree.cpp
+++ b/scene/main/scene_tree.cpp
@@ -2073,8 +2073,6 @@ SceneTree::SceneTree() {
 	root->set_as_audio_listener_2d(true);
 	current_scene = NULL;
 
-	int ref_atlas_size = GLOBAL_DEF("rendering/quality/reflections/atlas_size", 2048);
-	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/reflections/atlas_size", PropertyInfo(Variant::INT, "rendering/quality/reflections/atlas_size", PROPERTY_HINT_RANGE, "0,8192,or_greater")); //next_power_of_2 will return a 0 as min value
 	int msaa_mode = GLOBAL_DEF("rendering/quality/filters/msaa", 0);
 	ProjectSettings::get_singleton()->set_custom_property_info("rendering/quality/filters/msaa", PropertyInfo(Variant::INT, "rendering/quality/filters/msaa", PROPERTY_HINT_ENUM, "Disabled,2x,4x,8x,16x,AndroidVR 2x,AndroidVR 4x"));
 	root->set_msaa(Viewport::MSAA(msaa_mode));
diff --git a/scene/resources/surface_tool.cpp b/scene/resources/surface_tool.cpp
index fc5c906bd4..fa177d03fb 100644
--- a/scene/resources/surface_tool.cpp
+++ b/scene/resources/surface_tool.cpp
@@ -537,58 +537,36 @@ Vector<SurfaceTool::Vertex> SurfaceTool::create_vertex_array_from_triangle_array
 	Vector<float> warr = p_arrays[VS::ARRAY_WEIGHTS];
 
 	int vc = varr.size();
-
 	if (vc == 0)
 		return ret;
-	int lformat = 0;
 
-	const Vector3 *rv;
+	int lformat = 0;
 	if (varr.size()) {
 		lformat |= VS::ARRAY_FORMAT_VERTEX;
-		rv = varr.ptr();
 	}
-	const Vector3 *rn;
 	if (narr.size()) {
 		lformat |= VS::ARRAY_FORMAT_NORMAL;
-		rn = narr.ptr();
 	}
-	const float *rt;
 	if (tarr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TANGENT;
-		rt = tarr.ptr();
 	}
-	const Color *rc;
 	if (carr.size()) {
 		lformat |= VS::ARRAY_FORMAT_COLOR;
-		rc = carr.ptr();
 	}
-
-	const Vector2 *ruv;
 	if (uvarr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TEX_UV;
-		ruv = uvarr.ptr();
 	}
-
-	const Vector2 *ruv2;
 	if (uv2arr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TEX_UV2;
-		ruv2 = uv2arr.ptr();
 	}
-
-	const int *rb;
 	if (barr.size()) {
 		lformat |= VS::ARRAY_FORMAT_BONES;
-		rb = barr.ptr();
 	}
-
-	const float *rw;
 	if (warr.size()) {
 		lformat |= VS::ARRAY_FORMAT_WEIGHTS;
-		rw = warr.ptr();
 	}
 
 	for (int i = 0; i < vc; i++) {
-
 		Vertex v;
 		if (lformat & VS::ARRAY_FORMAT_VERTEX)
 			v.vertex = varr[i];
@@ -642,58 +620,36 @@ void SurfaceTool::_create_list_from_arrays(Array arr, List<Vertex> *r_vertex, Li
 	Vector<float> warr = arr[VS::ARRAY_WEIGHTS];
 
 	int vc = varr.size();
-
 	if (vc == 0)
 		return;
-	lformat = 0;
 
-	const Vector3 *rv;
+	lformat = 0;
 	if (varr.size()) {
 		lformat |= VS::ARRAY_FORMAT_VERTEX;
-		rv = varr.ptr();
 	}
-	const Vector3 *rn;
 	if (narr.size()) {
 		lformat |= VS::ARRAY_FORMAT_NORMAL;
-		rn = narr.ptr();
 	}
-	const float *rt;
 	if (tarr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TANGENT;
-		rt = tarr.ptr();
 	}
-	const Color *rc;
 	if (carr.size()) {
 		lformat |= VS::ARRAY_FORMAT_COLOR;
-		rc = carr.ptr();
 	}
-
-	const Vector2 *ruv;
 	if (uvarr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TEX_UV;
-		ruv = uvarr.ptr();
 	}
-
-	const Vector2 *ruv2;
 	if (uv2arr.size()) {
 		lformat |= VS::ARRAY_FORMAT_TEX_UV2;
-		ruv2 = uv2arr.ptr();
 	}
-
-	const int *rb;
 	if (barr.size()) {
 		lformat |= VS::ARRAY_FORMAT_BONES;
-		rb = barr.ptr();
 	}
-
-	const float *rw;
 	if (warr.size()) {
 		lformat |= VS::ARRAY_FORMAT_WEIGHTS;
-		rw = warr.ptr();
 	}
 
 	for (int i = 0; i < vc; i++) {
-
 		Vertex v;
 		if (lformat & VS::ARRAY_FORMAT_VERTEX)
 			v.vertex = varr[i];