For questions about (suspected) incorrect behavior of a compiler. Use with the appropriate language tag and, where applicable, with the tag for the compiler in question.
Questions tagged [compiler-bug]
309 questions
33
votes
4 answers
Visual Studio 2012 different values Release/Debug mode
This code produces different values in MSVS 2012, Windows 7, when switching between Debug and Release mode:
#include
using namespace std;
int A[20000];
int main() {
int shift = 0;
int Period = 30;
//Fill array
for(int i…
user3023605
- 459
- 5
- 11
32
votes
1 answer
Double free in the C++ standard library using only std::function and std::shared_pointer
I recently came across a weird double-free bug in a program when capturing a shared_ptr in a lambda. I was able to reduce it this the following minimal example:
#include
#include
struct foo {
std::function…
Patrick Ziegler
- 787
- 1
- 7
- 20
32
votes
2 answers
VBA takes wrong branch at If-statement - severe compiler bug?
The question mark in the title is only there because I'm very reluctant to call anything a compiler bug, but in this case, I'd be surprised if anyone could explain this behavior in any other way.
The code to reproduce the problem is very, very…
GWD
- 3,081
- 14
- 30
29
votes
2 answers
Possible compiler bug in Visual C++ 2012 (x86)?
I'm currently experiencing random floating point errors when compiling for x86 targets using VC++ 11 (CTP Update 1). See the short example "test.cpp" below, and compile using:
cl /GL /O2 /EHsc test.cpp /link /MACHINE:X86
The output should be 10 ==…
Daniel Gehriger
- 7,339
- 2
- 34
- 55
28
votes
3 answers
Maybe a C# compiler bug in Visual Studio 2015
I think this is a compiler bug.
The following console application compiles und executes flawlessly when compiled with VS 2015:
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
var…
Peter Perot
- 1,003
- 1
- 10
- 15
26
votes
2 answers
C# compiler bug? Object initializer syntax used for write-only property in Expression makes csc crash
You may consider this a bug report, however I'm curious if I am terribly wrong here, or if there is an explanation from Eric or someone else at Microsoft.
Update
This is now posted as a bug on Microsoft Connect.
Description
Consider the following…
Dan Abramov
- 264,556
- 84
- 409
- 511
26
votes
1 answer
Visual Studio 2019 does not handle aggregate initialization of dynamic array of structs correctly
The code below prints garbage (or zeroes) if compiled with VC++ 2017 and "1122" if compiled with GCC or Clang (https://rextester.com/JEV81255). Is it bug of VC++ or I'm missing something here?
#include
struct Item {
int id;
int…
user10101
- 1,704
- 2
- 20
- 49
26
votes
2 answers
(Known) compiler bug in VC12?
This program, when compiled with VC12 (in Visual Studio 2013 RTM)[1] leads to a crash (in all build configurations), when really it shouldn't:
#include
void foo(std::string const& oops = {})
{
}
int main()
{
foo();
}
I know of two…
sehe
- 374,641
- 47
- 450
- 633
25
votes
2 answers
Is this failing test that adds zero to a null pointer undefined behaviour, a compiler bug, or something else?
I wrote a lightweight string_view wrapper for a C++14 project, and with MSVC 2017 it is triggering a static_assert at compile-time, yet the same code at run-time is passes the regular assert. My question is, is this a compiler bug, manifest…
Charles L Wilcox
- 1,126
- 8
- 18
24
votes
2 answers
Why are generic and non-generic structs treated differently when building expression that lifts operator == to nullable?
This looks like a bug in lifting to null of operands on generic structs.
Consider the following dummy struct, that overrides operator==:
struct MyStruct
{
private readonly int _value;
public MyStruct(int val) { this._value = val; }
…
sinelaw
- 16,205
- 3
- 49
- 80
22
votes
2 answers
Why does the compiler evaluate remainder MinValue % -1 different than runtime?
I think this looks like a bug in the C# compiler.
Consider this code (inside a method):
const long dividend = long.MinValue;
const long divisor = -1L;
Console.WriteLine(dividend % divisor);
It compiles with no errors (or warnings). Seems like a…
Jeppe Stig Nielsen
- 60,409
- 11
- 110
- 181
21
votes
8 answers
"redundant cast to java.lang.Object" warning for necessary cast
Consider this Minimal, Reproducible Example :
interface Code {
static void main(String[] args) {
symbol(
String.valueOf(
true ? 'a' :
true ? 'b' :
true ? 'c' :
…
Tom Hawtin - tackline
- 145,806
- 30
- 211
- 305
21
votes
1 answer
brace-or-equal-Initializer in unions
Related: How to initialize a non-POD member in Union
The standard says
At most one non-static data member of a union may have a brace-or-equal-initializer.
But
struct Point {
Point() {}
Point(int x, int y): x_(x), y_(y) {}
int x_,…
Sebastian Mach
- 38,570
- 8
- 95
- 130
20
votes
0 answers
Using await inside Interlocked.Exchange crashes the C# compiler
Ignore for a moment the absurdity of awaiting an Enumerable.Range call. It's just there to elicit the crash-y behavior. It just as easily could be a method that's doing some network IO to build a collection of value objects. (Indeed, this was where…
rianjs
- 7,767
- 5
- 24
- 40
19
votes
1 answer
Why does this code using __LINE__ compile under MSVC in Release mode, but not in Debug mode?
Consider this program:
#include
template
constexpr int adds(const int& a, const int& b) {
if (Debug)
std::cout << __FUNCTION__ << " called on line " << Line << '\n';
return (a +…
Francis Cugler
- 7,788
- 2
- 28
- 59