Use "literal" term where appropriate in shader language.

Previously we were using "constant" to describe all
instances of immutable declarations, whether that was
an inline literal or an actual declared constant variable.

This lack of disambiguation also resulted in some misleading
error messages, ie: "expected integer constant" where only
a literal is actually valid (and passing an actual constant
like PI would fail with that exact error message).

This also improves a few error messages that only stated
the expectation of an integer literal when it was more appropriate
to say an integer OR float literal.

drivers/gles3/storage/material_storage.cpp

@@ -573,7 +573,7 @@ Variant ShaderData::get_default_parameter(const StringName &p_parameter) const {
 	if (uniforms.has(p_parameter)) {
 		ShaderLanguage::ShaderNode::Uniform uniform = uniforms[p_parameter];
 		Vector<ShaderLanguage::Scalar> default_value = uniform.default_value;
-		return ShaderLanguage::constant_value_to_variant(default_value, uniform.type, uniform.array_size, uniform.hint);
+		return ShaderLanguage::literal_value_to_variant(default_value, uniform.type, uniform.array_size, uniform.hint);
 	}
 	return Variant();
 }
@@ -626,7 +626,7 @@ void ShaderData::get_instance_param_list(List<RendererMaterialStorage::InstanceS
 		p.info = ShaderLanguage::uniform_to_property_info(E.value);
 		p.info.name = E.key; //supply name
 		p.index = E.value.instance_index;
-		p.default_value = ShaderLanguage::constant_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
+		p.default_value = ShaderLanguage::literal_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
 		p_param_list->push_back(p);
 	}
 }

servers/rendering/dummy/storage/material_storage.cpp

@@ -275,7 +275,7 @@ void MaterialStorage::material_get_instance_shader_parameters(RID p_material, Li
 			p.info = ShaderLanguage::uniform_to_property_info(E.value);
 			p.info.name = E.key; //supply name
 			p.index = E.value.instance_index;
-			p.default_value = ShaderLanguage::constant_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
+			p.default_value = ShaderLanguage::literal_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
 			r_parameters->push_back(p);
 		}
 	}

servers/rendering/renderer_rd/storage_rd/material_storage.cpp

@@ -569,7 +569,7 @@ Variant MaterialStorage::ShaderData::get_default_parameter(const StringName &p_p
 	if (uniforms.has(p_parameter)) {
 		ShaderLanguage::ShaderNode::Uniform uniform = uniforms[p_parameter];
 		Vector<ShaderLanguage::Scalar> default_value = uniform.default_value;
-		return ShaderLanguage::constant_value_to_variant(default_value, uniform.type, uniform.array_size, uniform.hint);
+		return ShaderLanguage::literal_value_to_variant(default_value, uniform.type, uniform.array_size, uniform.hint);
 	}
 	return Variant();
 }
@@ -622,7 +622,7 @@ void MaterialStorage::ShaderData::get_instance_param_list(List<RendererMaterialS
 		p.info = ShaderLanguage::uniform_to_property_info(E.value);
 		p.info.name = E.key; //supply name
 		p.index = E.value.instance_index;
-		p.default_value = ShaderLanguage::constant_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
+		p.default_value = ShaderLanguage::literal_value_to_variant(E.value.default_value, E.value.type, E.value.array_size, E.value.hint);
 		p_param_list->push_back(p);
 	}
 }

servers/rendering/shader_compiler.cpp

@@ -1086,28 +1086,28 @@ String ShaderCompiler::_dump_node_code(const SL::Node *p_node, int p_level, Gene
 			}
 
 		} break;
-		case SL::Node::NODE_TYPE_CONSTANT: {
-			SL::ConstantNode *cnode = (SL::ConstantNode *)p_node;
+		case SL::Node::NODE_TYPE_LITERAL: {
+			SL::LiteralNode *lnode = (SL::LiteralNode *)p_node;
 
-			if (cnode->array_size == 0) {
-				return get_constant_text(cnode->datatype, cnode->values);
+			if (lnode->array_size == 0) {
+				return get_constant_text(lnode->datatype, lnode->values);
 			} else {
-				if (cnode->get_datatype() == SL::TYPE_STRUCT) {
-					code += _mkid(cnode->struct_name);
+				if (lnode->get_datatype() == SL::TYPE_STRUCT) {
+					code += _mkid(lnode->struct_name);
 				} else {
-					code += _typestr(cnode->datatype);
+					code += _typestr(lnode->datatype);
 				}
 				code += "[";
-				code += itos(cnode->array_size);
+				code += itos(lnode->array_size);
 				code += "]";
 				code += "(";
-				for (int i = 0; i < cnode->array_size; i++) {
+				for (int i = 0; i < lnode->array_size; i++) {
 					if (i > 0) {
 						code += ",";
 					} else {
 						code += "";
 					}
-					code += _dump_node_code(cnode->array_declarations[0].initializer[i], p_level, r_gen_code, p_actions, p_default_actions, p_assigning);
+					code += _dump_node_code(lnode->array_declarations[0].initializer[i], p_level, r_gen_code, p_actions, p_default_actions, p_assigning);
 				}
 				code += ")";
 			}