vingeldal created this revision.
Herald added subscribers: cfe-commits, kbarton, xazax.hun, nemanjai.
Herald added a project: clang.
vingeldal added a comment.
Herald added a subscriber: wuzish.
After looking in to it I got less certain of where the error lies and
eventually I got uncertain if this even is a false negative, so I started out
with just posting a change where the unit test is updated to detect the issue.
This is just to have a start for a discussion of how this should actually work
and what is the best way forward.
The purpose of the rule is to avoid code which causes hidden dependencies. The
given example of a potential false positive is a free function with a static
variable.
Now, wouldn't a static variable inside a function body make the function
stateful thereby risking that the function gives different results for the same
input, in ways that might look arbitrary or random to the caller.
I think that might actually be a good example of what the rule is meant to
prevent so maybe this isn't a false positive after all?
There was a post merge comment about a possible false negative for this check:
https://reviews.llvm.org/D70265
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D77461
Files:
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
Index:
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
===================================================================
---
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
+++
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
@@ -231,7 +231,8 @@
// CHECKING AGAINST FALSE POSITIVES INSIDE FUNCTION SCOPE /////////////////////
int main() {
for (int i = 0; i < 3; ++i) {
+ static int staticNonConstLoopVariable = 42;
int nonConstLoopVariable = 42;
- nonConstInt = nonConstLoopVariable + i;
+ nonConstInt = nonConstLoopVariable + i + staticNonConstLoopVariable;
}
}
Index: clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-avoid-non-const-global-variables.cpp
@@ -231,7 +231,8 @@
// CHECKING AGAINST FALSE POSITIVES INSIDE FUNCTION SCOPE /////////////////////
int main() {
for (int i = 0; i < 3; ++i) {
+ static int staticNonConstLoopVariable = 42;
int nonConstLoopVariable = 42;
- nonConstInt = nonConstLoopVariable + i;
+ nonConstInt = nonConstLoopVariable + i + staticNonConstLoopVariable;
}
}
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