Summary:
Previously, we considered a function which modifies its parameters to be impure even though it might not be modifying the underlying value. This resulted in FPs like the following program in Java:
```
void fresh_pure(int[] a) {
a = new int[1];
}
```
Similarly, in C++, we considered the following program as impure because it was writing to `s`:
```
Simple* reassign_pure(Simple* s) {
s = new Simple{2};
return s;
}
```
This diff fixes that issue by starting the check for address equivalnce in pre-post not directly from the addresses of the stack variables, but from the addresses pointed to by these stack variables. That means, we only consider things to be impure if the actual values pointed by the parameters change.
Reviewed By: skcho
Differential Revision: D18113846
fbshipit-source-id: 3d7c712f3
master
Ezgi Çiçek5 years agocommitted byFacebook Github Bot
codetoanalyze/cpp/impurity/invalid_test.cpp, Simple::operator=, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function Simple::operator=,parameter `this` of Simple::operator=,parameter `this` modified here]
codetoanalyze/cpp/impurity/invalid_test.cpp, delete_param_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function delete_param_impure,parameter `s` of delete_param_impure,parameter `s` was invalidated by `delete` here]
codetoanalyze/cpp/impurity/invalid_test.cpp, double_free_global_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function double_free_global_impure]
codetoanalyze/cpp/impurity/invalid_test.cpp, double_free_global_impure, 2, USE_AFTER_FREE, no_bucket, ERROR, [invalidation part of the trace starts here,global variable `global_pointer` accessed here,when calling `free_global_pointer_impure` here,global variable `global_pointer` accessed here,was invalidated by call to `free()`,use-after-lifetime part of the trace starts here,global variable `global_pointer` accessed here,when calling `free_global_pointer_impure` here,global variable `global_pointer` accessed here,invalid access occurs here]
codetoanalyze/cpp/impurity/invalid_test.cpp, free_global_pointer_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function free_global_pointer_impure,global variable `global_pointer` accessed here,global variable `global_pointer` was invalidated by call to `free()` here]
codetoanalyze/cpp/impurity/invalid_test.cpp, free_param_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function free_param_impure,parameter `x` of free_param_impure,parameter `x` was invalidated by call to `free()` here]
codetoanalyze/cpp/impurity/invalid_test.cpp, reassign_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function reassign_impure,parameter `s` of reassign_impure,parameter `s` modified here]
codetoanalyze/cpp/impurity/invalid_test.cpp, reassign_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function reassign_impure,parameter `s` of reassign_impure,when calling `Simple::operator=` here,parameter `this` of Simple::operator=,parameter `s` modified here]
codetoanalyze/cpp/impurity/invalid_test.cpp, swap_address_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function swap_address_impure,parameter `rhs` of swap_address_impure,when calling `Simple::operator=` here,parameter `this` of Simple::operator=,parameter `rhs` modified here,parameter `lhs` of swap_address_impure,when calling `Simple::operator=` here,parameter `this` of Simple::operator=,parameter `lhs` modified here]
codetoanalyze/cpp/impurity/invalid_test.cpp, swap_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function swap_impure,parameter `s2` of swap_impure,when calling `Simple::operator=` here,parameter `this` of Simple::operator=,parameter `s2` modified here,parameter `s1` of swap_impure,when calling `Simple::operator=` here,parameter `this` of Simple::operator=,parameter `s1` modified here]
codetoanalyze/cpp/impurity/param_test.cpp, create_cycle_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function create_cycle_impure,parameter `x` of create_cycle_impure,parameter `x` modified here]
codetoanalyze/cpp/impurity/param_test.cpp, invalidate_local_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function invalidate_local_impure,parameter `pp` of invalidate_local_impure,parameter `pp` modified here]
codetoanalyze/cpp/impurity/param_test.cpp, modify_mut_ref_impure, 0, IMPURE_FUNCTION, no_bucket, ERROR, [Impure function modify_mut_ref_impure,parameter `x` of modify_mut_ref_impure,parameter `x` modified here]
Ezgi Çiçek
5 years ago
committed by
Facebook Github Bot