![И ЦИЯ
5
enumeration
enum Foo {
e1,
e2,
eCount
};
const char* FooToString(Foo x);
int main() {
std::cout << FooToString(e2) << std::endl;
return 0;
}
enum Foo {
e1,
eCount
};
const char xxx [] = «can you see me?!!»
const char* msg [eCount] = {
«e1»
};
const char* canYouSeeMe = xxx;
const char* FooToString(Foo x) {return msg[x];}](https://image.slidesharecdn.com/28-150827190830-lva1-app6891/85/One-definition-rule-5-320.jpg)
![И ЦИЯ
7
pragma pack
#pragma pack(push, 1)
struct C {
char c;
uint32_t x;
};
#pragma pack(pop)
void Modify(C* c, size_t pos);
int main() {
std::string x = «0»;
C c[8] = {0};
Modify(c, 6);
std::cout << x << std::endl;
return 0;
}
struct C {
char c;
uint32_t x;
};
void Modify(C* c, size_t pos) {
c[pos].x += 1;
}](https://image.slidesharecdn.com/28-150827190830-lva1-app6891/85/One-definition-rule-7-320.jpg)
One definition rule - что это такое, и как с этим жить
- 1. ONE DEFINITION RULE – HOW TO LIVE WITH IT Alexey Kutumov Software engineer at Kaspersky Lab
- 2. CONTENTS 2 И ЦИЯ И Е Ы CLANG/ODR-CHECK3 2 1
- 3. И ЦИЯ
- 4. ODR-CHECK 4 Compilation/linking compile compile compile .cpp .obj .exe .cpp .obj .cpp .obj ar .lib link
- 5. И ЦИЯ 5 enumeration enum Foo { e1, e2, eCount }; const char* FooToString(Foo x); int main() { std::cout << FooToString(e2) << std::endl; return 0; } enum Foo { e1, eCount }; const char xxx [] = «can you see me?!!» const char* msg [eCount] = { «e1» }; const char* canYouSeeMe = xxx; const char* FooToString(Foo x) {return msg[x];}
- 6. И ЦИЯ 6 struct A : private boost::noncopyable { A() : x(«0») {} const std::string x; int y; }; void Modify(A& a); int main() { A a; Modify(a); std::cout << a.x << std::endl; return 0; } struct A : private boost::noncopyable { A(); int x; const std::string y; }; void Modify(A& a) { a.x += 1; }
- 7. И ЦИЯ 7 pragma pack #pragma pack(push, 1) struct C { char c; uint32_t x; }; #pragma pack(pop) void Modify(C* c, size_t pos); int main() { std::string x = «0»; C c[8] = {0}; Modify(c, 6); std::cout << x << std::endl; return 0; } struct C { char c; uint32_t x; }; void Modify(C* c, size_t pos) { c[pos].x += 1; }
- 8. И ЦИЯ 8 К • , , • + Х assert, core dump, , • - « » •Code review • - , •gcc –Wodr, gold –detect-odr-violations • + • - , false positive •Amalgamation (sqlite) • + • - • -
- 9. И Е Ы
- 10. И Е Ы 10 3.2 C++ • , , , • non-inline ODR- used • , , complete.
- 11. И Е Ы 11 3.2 C++ • non-inline ODR-used. • , , inline external linkage, , . : • К • В , TU
- 12. И Е Ы 12 3.2 C++ Undefined Behavior
- 13. И Е Ы 13 Т •А • •Т IDE, .
- 14. И Е Ы 14 #pragma detect_mismatch #pragma detect_mismatch(«my_name», «my_value1») /// cpp1.cpp #pragma detect_mismatch(«my_name», «my_value2») /// cpp2.cpp cpp2.obj : error LNK2038: mismatch detected for 'my_name': value ‘my_value ' doesn't match value ‘my_value ' in cpp1.obj dumpbin /ALL cpp1.obj Linker Directives ----------------- /FAILIFMISMATCH:"my_name=my_value1" /DEFAULTLIB:"MSVCRTD" /DEFAULTLIB:"OLDNAMES"
- 15. CLANG/ODR-CHECK
- 16. CLANG 16 clang
- 17. ODR-CHECK 17 Compilation/linking compile compile compile .cpp .obj .exe .cpp .obj .cpp .obj ar .lib link
- 18. ODR-CHECK 18 Checking for ODR violations emit-ast emit-ast emit-ast .cpp .ast .ast .cpp .ast .cpp .ast merge-ast .ast merge-ast
- 20. ODR-CHECK 20 Storing AST to file .cpp token stream ASTContext Preprocessor/Lexer Sema .ast ASTFrontendAction (GeneratePCHAction)
- 21. ODR-CHECK 21 Merging ASTs cannot import unsupportОН noНО: … .ast .ast .ast .ast ASTMergeAction
- 22. ODR-CHECK 22 Merging ASTs • : • • • ODR, •
- 23. ODR-CHECK 23 RecursiveASTVisitor namespace m { struct X { int a; }; } clang ../main.cpp -Xclang -ast-dump -fsyntax-only http://clang.llvm.org/docs/RAVFrontendAction.html
- 24. ODR-CHECK 24 ASTImporter TranslationUnitDecl (From) TranslationUnitDecl (To) |-Node |-Node `-Node `-Node `-Node `-Node ASTNodeImporter
- 25. ODR-CHECK 25 ASTNodeImporter namespace m { /// 4. NamespaceDecl(NamedDecl, DeclContext) namespace n { /// 3. NamespaceDecl (NamedDecl, DeclContext) struct X { /// 2. CXXRecordDecl (..., TypeDecl, DeclContext) struct Y { /// 1. CXXRecordDecl (..., TypeDecl, DeclContext) int a; /// <- IMPORT }; }; } }
- 26. ODR-CHECK 26 StructuralEquivalenceContext namespace m { struct X { int a; long b; }; struct Y { X x; int b; }; struct Z { int b; }; } namespace m { struct X { int a; long b; }; struct Y { X x; long b; }; struct Z { int a; }; }
- 27. ODR-CHECK 27 И cmake clang++ -DMY_SUPER_DEFINE –Wall –I/my/include –emit-ast source_file.cpp –o source_file.ast clang++ -cc1 –emit-pch –o lib_file.ast -ast-merge source_file1.ast –ast-merge source_file2.ast cmake ../src -DCMAKE_TOOLCHAIN_FILE=d:/tools/ClangOdrCheckToolchain.cmake –D... make
- 28. ODR-CHECK 28 Sample output namespace m { struct X { int x; #if defined (M1) int z; #endif /* M1 */ }; }
- 29. ODR-CHECK 29 Sample output In file included from d:pixelprojectsodr-checkodr-check-testsrcdatasrcm1.cpp:3: d:pixelprojectsodr-checkodr-check-testsrcdatasrc/h1.h:11:8: warning: type 'struct m::X' has incompatible definitions in different translation units struct X ^ d:pixelprojectsodr-checkodr-check-testsrcdatasrc/h1.h:16:7: note: field 'z' has type 'int' here int z; ^ d:pixelprojectsodr-checkodr-check-testsrcdatasrc/h1.h:11:8: note: no corresponding field here struct X ^
- 30. ODR-CHECK 30 ИТ • PoC: https://github.com/prograholic/clang/tree/odr-check • Production Ready (milestone: check tool on some Boost libraries) • Memory consumption (huge ASTs) • Minimize import amount (static, unnamed namespaces, templates) •Merge changes to clang/master
- 31. LET'S TALK? mail: [email protected] twitter: @prograholic https://github.com/prograholic/odr-check https://github.com/prograholic/clang/tree/odr-check