https://bugs.llvm.org/show_bug.cgi?id=36477
Bug ID: 36477
Summary: clang-analyzer-core.uninitialized.Assign: False
positive with reinterpret_cast
Product: clang
Version: unspecified
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Static Analyzer
Assignee: dcough...@apple.com
Reporter: r...@eatnumber1.com
CC: llvm-bugs@lists.llvm.org
I've been encountering a case where Clang Static Analyzer raises
clang-analyzer-core.uninitialized.Assign. I've narrowed down the culprit code
to the following sample case:
struct myint {
int d;
};
struct foo {
myint a;
};
int myfn1() {
foo myfoo {5};
const unsigned char *a = reinterpret_cast<const unsigned char
*>(&myfoo.a);
char ret = a[1];
return ret;
}
The warning generated is:
$ scan-build clang++ -std=c++11 -c -O0 ~/a.cc
scan-build: Using '/usr/bin/clang' for static analysis
/usr/local/google/home/eatnumber1/a.cc:12:3: warning: Assigned value is garbage
or undefined
char ret = a[1];
^~~~~~~~ ~~~~
1 warning generated.
scan-build: 1 bugs found.
scan-build: Run 'scan-view /tmp/scan-build-2017-10-13-151811-27304-1' to
examine bug reports.
If I change `struct foo` to the following:
struct foo {
int a;
};
then the warning is not emitted.
What's going on here?
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