gcc -O3 标志导致 -Winline“调用不太可能，代码大小会增加”警告

Question

我使用的是 Ubuntu 14.04 和 gcc 4.9.3。我遇到一个奇怪的问题，当我启用 O3 优化时，会弹出一些“调用不太可能，代码大小会增长 [-Werror=inline]”错误。我的代码中没有 inline 关键字。为什么 gcc 内联优化代码以至于触发它自己的警告？

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显然禁用 -Winline 会编译，但是有更好的方法来解决这个问题吗？

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我正在使用的库是点云库，为了完整性，代码如下所示。

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我的 CMakeLists

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cmake_minimum_required(VERSION 2.8)\nproject(Test)\n\nset(PROJECT_SRCS\n${PROJECT_SOURCE_DIR}/Test.cpp\n)\n\nset(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -W -Werror -Winline")\n\n# causes error\nset(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")\n\nfind_package( PCL 1.7 REQUIRED )\n\ninclude_directories(${PCL_INCLUDE_DIRS})\n\nadd_executable(${PROJECT_NAME} ${PROJECT_SRCS})\n\ntarget_link_libraries(${PROJECT_NAME} ${PCL_LIBRARIES})\n

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测试.cpp

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#include <string>\n#include <vector>\n\n#include "pcl/common/common_headers.h"\n#include "pcl/io/obj_io.h"\n#include "pcl/io/ply_io.h"\n#include "pcl/io/vtk_lib_io.h"\n#include "pcl/visualization/pcl_visualizer.h"\n\nint main(){\n  pcl::TextureMesh mesh;\n  pcl::PointCloud<pcl::PointNormal> xyz;\n\n  pcl::PointNormal point1;\n  pcl::PointNormal point2;\n  pcl::PointNormal point3;\n  point1.x = 0;\n  point2.x = 1;\n  point3.x = 0;\n  point1.y = 0;\n  point2.y = 0;\n  point3.y = 1;\n  point1.z = 2;\n  point2.z = 2;\n  point3.z = 2;\n  xyz.push_back(point1);\n  xyz.push_back(point2);\n  xyz.push_back(point3);\n  pcl::toPCLPointCloud2(xyz, mesh.cloud);\n\n  std::vector<pcl::Vertices> mesh_poly;\n  std::vector<Eigen::Vector2f, Eigen::aligned_allocator<Eigen::Vector2f> > mesh_tex;\n  pcl::TexMaterial mesh_material;\n\n  pcl::Vertices v;\n  v.vertices.push_back(0);\n  v.vertices.push_back(1);\n  v.vertices.push_back(2);\n  mesh_poly.push_back(v);\n\n  Eigen::Vector2f tex1;\n  Eigen::Vector2f tex2;\n  Eigen::Vector2f tex3;\n  tex1(0) = -1.0;\n  tex1(1) = 0.0;\n  tex2(0) = -1.0;\n  tex2(1) = 1.0;\n  tex3(0) = 2.0;\n  tex3(1) = 0.0;\n\n  mesh_tex.push_back(tex1);\n  mesh_tex.push_back(tex2);\n  mesh_tex.push_back(tex3);\n\n  mesh_material.tex_file = "lena.png";\n  mesh_material.tex_name = "material_0";\n\n  mesh.tex_polygons.push_back(mesh_poly);\n  mesh.tex_coordinates.push_back(mesh_tex);\n  mesh.tex_materials.push_back(mesh_material);\n\n  pcl::io::saveOBJFile("out.obj", mesh);\n\n  return 0;\n}\n

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编辑：更新错误消息

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In file included from /usr/local/include/pcl-1.8/pcl/io/obj_io.h:40:0,\n                 from /home/david/test/Test.cpp:5:\n/usr/local/include/pcl-1.8/pcl/TextureMesh.h: In function \xe2\x80\x98int main()\xe2\x80\x99:\n/usr/local/include/pcl-1.8/pcl/TextureMesh.h:50:10: error: inlining failed in call to \xe2\x80\x98pcl::TexMaterial::~TexMaterial()\xe2\x80\x99: call is unlikely and code size would grow [-Werror=inline]\n   struct TexMaterial\n          ^\n/home/david/test/Test.cpp:37:20: error: called from here [-Werror=inline]\n   pcl::TexMaterial mesh_material;\n                ^\nIn file included from /usr/local/include/pcl-1.8/pcl/io/obj_io.h:40:0,\n                 from /home/david/test/Test.cpp:5:\n/usr/local/include/pcl-1.8/pcl/TextureMesh.h:91:10: error: inlining     failed in call to \xe2\x80\x98pcl::TextureMesh::~TextureMesh()\xe2\x80\x99: call is unlikely and code size would grow [-Werror=inline]\n   struct TextureMesh\n          ^\n/home/david/test/Test.cpp:14:20: error: called from here [-Werror=inline]\n   pcl::TextureMesh mesh;\n                    ^\nIn file included from /usr/local/include/pcl-1.8/pcl/io/obj_io.h:40:0,\n             from /home/david/test/Test.cpp:5:\n/usr/local/include/pcl-1.8/pcl/TextureMesh.h:50:10: error: inlining failed in call to \xe2\x80\x98pcl::TexMaterial::~TexMaterial()\xe2\x80\x99: call is unlikely and code size would grow [-Werror=inline]\n   struct TexMaterial\n          ^\n/home/david/test/Test.cpp:37:20: error: called from here [-Werror=inline]\n   pcl::TexMaterial mesh_material;\n                    ^\nIn file included from /usr/local/include/pcl-1.8/pcl/io/obj_io.h:40:0,\n             from /home/david/test/Test.cpp:5:\n/usr/local/include/pcl-1.8/pcl/TextureMesh.h:91:10: error: inlining failed in call to \xe2\x80\x98pcl::TextureMesh::~TextureMesh()\xe2\x80\x99: call is unlikely and code size would grow [-Werror=inline]\n   struct TextureMesh\n          ^\n/home/david/test/Test.cpp:14:20: error: called from here [-Werror=inline]\n   pcl::TextureMesh mesh;\n                ^\ncc1plus: all warnings being treated as errors\nmake[2]: *** [CMakeFiles/Test.dir/Test.cpp.o] Error 1\nmake[1]: *** [CMakeFiles/Test.dir/all] Error 2\nmake: *** [all] Error 2\n

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Answer 1

类/结构的使用可能具有内联成员，即使代码中没有明确指出。

例如，pcl::TextureMesh结构体将有一个隐式析构函数，根据 C++ 标准：

隐式声明的析构函数是其类的内联公共成员。