Cycles: Use explicit qualifier for single-argument constructors

Almost in all cases we want such constructors to be explicit, there are
exceptions but only in few places.

intern/cycles/render/attribute.h

@@ -134,8 +134,8 @@ public:
 	AttributeElement triangle_element, curve_element;
 	int triangle_offset, curve_offset;
 
-	AttributeRequest(ustring name_);
-	AttributeRequest(AttributeStandard std);
+	explicit AttributeRequest(ustring name_);
+	explicit AttributeRequest(AttributeStandard std);
 };
 
 /* AttributeRequestSet

intern/cycles/render/buffers.h

@@ -73,7 +73,7 @@ public:
 	/* random number generator state */
 	device_vector<uint> rng_state;
 
-	RenderBuffers(Device *device);
+	explicit RenderBuffers(Device *device);
 	~RenderBuffers();
 
 	void reset(Device *device, BufferParams& params);

intern/cycles/render/graph.h

@@ -177,7 +177,7 @@ public:
 
 class ShaderNode {
 public:
-	ShaderNode(const char *name);
+	explicit ShaderNode(const char *name);
 	virtual ~ShaderNode();
 
 	ShaderInput *input(const char *name);

intern/cycles/render/image.h

@@ -32,7 +32,7 @@ class Progress;
 
 class ImageManager {
 public:
-	ImageManager(const DeviceInfo& info);
+	explicit ImageManager(const DeviceInfo& info);
 	~ImageManager();
 
 	enum ImageDataType {

intern/cycles/render/nodes.h

@@ -75,7 +75,7 @@ public:
 
 class TextureNode : public ShaderNode {
 public:
-	TextureNode(const char *name_) : ShaderNode(name_) {}
+	explicit TextureNode(const char *name_) : ShaderNode(name_) {}
 	TextureMapping tex_mapping;
 
 	virtual bool equals(const ShaderNode *other) {
@@ -87,7 +87,7 @@ public:
 /* Any node which uses image manager's slot should be a subclass of this one. */
 class ImageSlotTextureNode : public TextureNode {
 public:
-	ImageSlotTextureNode(const char *name_) : TextureNode(name_) {
+	explicit ImageSlotTextureNode(const char *name_) : TextureNode(name_) {
 		special_type = SHADER_SPECIAL_TYPE_IMAGE_SLOT;
 	}
 	int slot;
@@ -379,7 +379,7 @@ public:
 
 class BsdfNode : public ShaderNode {
 public:
-	BsdfNode(bool scattering = false);
+	explicit BsdfNode(bool scattering = false);
 	SHADER_NODE_BASE_CLASS(BsdfNode);
 
 	bool has_spatial_varying() { return true; }

intern/cycles/render/session.h

@@ -129,7 +129,7 @@ public:
 	function<void(RenderTile&)> write_render_tile_cb;
 	function<void(RenderTile&)> update_render_tile_cb;
 
-	Session(const SessionParams& params);
+	explicit Session(const SessionParams& params);
 	~Session();
 
 	void start();

intern/cycles/render/svm.h

@@ -150,7 +150,7 @@ protected:
 
 	/* Global state of the compiler accessible from the compilation routines. */
 	struct CompilerState {
-		CompilerState(ShaderGraph *graph);
+		explicit CompilerState(ShaderGraph *graph);
 
 		/* ** Global state, used by various compilation steps. ** */