Questions tagged [compiler-warnings]
Messages emitted by a compiler which indicate potential problems in code or configuration.
compiler-warnings
2,707
questions
520
votes
14
answers
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views
How do you disable dead code warnings at the crate level in Rust?
While tinkering in Rust, I repeatedly encountered a lot of dead code warnings that made it difficult to focus. I tried using the outer attribute #[allow(dead_code)], but it only silences one warning ...
- 23.7k
354
votes
21
answers
42k
views
Why should I always enable compiler warnings?
I often hear that when compiling C and C++ programs I should "always enable compiler warnings". Why is this necessary? How do I do that?
Sometimes I also hear that I should "treat warnings as errors"...
- 117k
325
votes
10
answers
199k
views
What is the list of valid @SuppressWarnings warning names in Java?
What is the list of valid @SuppressWarnings warning names in Java?
The bit that comes in between the ("") in @SuppressWarnings("").
- 54.3k
322
votes
9
answers
234k
views
How to disable GCC warnings for a few lines of code
In Visual C++, it's possible to use #pragma warning (disable: ...). Also I found that in GCC you can override per file compiler flags. How can I do this for "next line", or with push/pop semantics ...
- 115k
299
votes
6
answers
192k
views
What is "android:allowBackup"?
Since the new ADT preview version (version 21), they have a new lint warning that tells me the next thing on the manifest file (in the application tag):
Should explicitly set android:allowBackup to ...
- 116k
294
votes
10
answers
1.2m
views
Message "warning: implicit declaration of function"
My compiler (GCC) is giving me the warning:
warning: implicit declaration of function
Why is it coming?
- 12.4k
259
votes
8
answers
107k
views
How can I turn on (literally) ALL of GCC's warnings?
I would like to enable—literally—all of the warnings that GCC has. (You'd think it would be easy...)
You'd think -Wall might do the trick, but nope! You still need -Wextra.
You'd think -Wextra might ...
- 207k
223
votes
11
answers
328k
views
Property getters and setters
With this simple class I am getting the compiler warning
Attempting to modify/access x within its own setter/getter
and when I use it like this:
var p: point = Point()
p.x = 12
I get an ...
- 13.7k
194
votes
4
answers
172k
views
Objective-C implicit conversion loses integer precision 'NSUInteger' (aka 'unsigned long') to 'int' warning
I'm working through some exercises and have got a warning that states:
Implicit conversion loses integer precision: 'NSUInteger' (aka 'unsigned long') to 'int'
#import <Foundation/Foundation.h&...
- 1,961
182
votes
6
answers
69k
views
What's the point of g++ -Wreorder?
The g++ -Wall option includes -Wreorder. What this option does is described below. It is not obvious to me why somebody would care (especially enough to turn this on by default in -Wall).
-Wreorder ...
- 8,028
175
votes
7
answers
18k
views
What does i = (i, ++i, 1) + 1; do?
After reading this answer about undefined behavior and sequence points, I wrote a small program:
#include <stdio.h>
int main(void) {
int i = 5;
i = (i, ++i, 1) + 1;
printf("%d\n"...
- 72.7k
146
votes
4
answers
111k
views
Override compile flags for single files
I would like to use a global set of flags for compiling a project, meaning that at my top-level CMakeLists.txt file I have specified:
ADD_DEFINITIONS ( -Wall -Weffc++ -pedantic -std=c++0x )
However, ...
- 1,793
143
votes
11
answers
59k
views
Custom Compiler Warnings
When using the ObsoleteAtribute in .Net it gives you compiler warnings telling you that the object/method/property is obsolete and somthing else should be used. I'm currently working on a project that ...
- 114k
133
votes
7
answers
297k
views
How can I compile without warnings being treated as errors?
The problem is that the same code that compiles well on Windows, is unable to compile on Ubuntu. Every time I get this error:
cc1: warnings being treated as errors
Now, it's big code base and I don'...
- 6,498
131
votes
10
answers
278k
views
How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to edit?
I'd like to know what switch you pass to the gcc compiler to turn off unused variable warnings? I'm getting errors out of boost on windows and I do not want to touch the boost code:
C:\boost_1_52_0/...
- 42.1k
127
votes
3
answers
34k
views
"Delegate subtraction has unpredictable result" in ReSharper/C#?
When using myDelegate -= eventHandler ReSharper (version 6) issues:
Delegate subtraction has unpredictable result
The rational behind this is explained by JetBrains here. The explanation makes ...
user166390
122
votes
8
answers
192k
views
Java Class.cast() vs. cast operator
Having being taught during my C++ days about evils of the C-style cast operator I was pleased at first to find that in Java 5 java.lang.Class had acquired a cast method.
I thought that finally we ...
- 45.2k
112
votes
7
answers
34k
views
How do I get rid of "[some event] never used" compiler warnings in Visual Studio?
For example, I get this compiler warning,
The event 'Company.SomeControl.SearchClick' is never used.
But I know that it's used because commenting it out throws me like 20 new warnings of XAML ...
- 10.3k
107
votes
6
answers
68k
views
Visual Studio warning level meanings?
On the build tab in a Web Application project I have a setting called "Warning Level". I can set a value from 0 to 4. What do these values mean? Will a value of 0 be more strict and generate more ...
- 48.4k
106
votes
8
answers
48k
views
How to detect unused methods and #import in Objective-C
After working a long time on an iPhone app, I realized that my code is quite dirty, containing several #import and methods that are not called or useful at all.
I would like to know if there's any ...
- 3,573
102
votes
10
answers
66k
views
How can I get rid of an "unused variable" warning in Xcode?
I understand exactly why unused variable warnings occur. I don't want to suppress them in general, because they are incredibly useful in most cases. However, consider the following (contrived) code.
...
- 16.3k
96
votes
11
answers
43k
views
How to intentionally cause a custom java compiler warning message?
I'm about to commit an ugly temporary hack in order to work around a blocking issue while we wait for an external resource to be fixed. Aside from marking it with a big scary comment and a bunch of ...
- 3,086
94
votes
4
answers
58k
views
Selectively disable GCC warnings for only part of a translation unit
What's the closest GCC equivalent to this MSVC preprocessor code?
#pragma warning( push ) // Save the current warning state.
#pragma warning( disable : 4723 ) // C4723: ...
- 17.1k
87
votes
4
answers
14k
views
Does there exist a static_warning?
I'm aware of this question which mentions Boost's "STATIC WARNING", but I'd like to ask again, specifically, how I could implement a static_warning which operates similarly to static_assert but only ...
- 470k
85
votes
7
answers
72k
views
Is using #pragma warning push/pop the right way to temporarily alter warning level?
Once in a while it's difficult to write C++ code that wouldn't emit warnings at all. Having warnings enabled is however a good idea. So it is often necessary to disable warnings around some specific ...
- 169k
83
votes
6
answers
38k
views
Why should I initialize member variables in the order they're declared in?
I was writing some code today and got a weird compile error, which seems to be caused by initializing member variables in a different order than they were declared.
Example:
class Test {
int a;
...
- 53.7k
78
votes
4
answers
31k
views
Ignore all warnings in a specific file using LLVM/Clang
There are some files in my iOS project that have some warnings, and I want to ignore those warnings. I don't want to disable warnings in the entire project (know how to do that), just some specific ...
- 2,157
77
votes
4
answers
53k
views
What does casting to `void` really do? [duplicate]
An often used statement like (void)x; allows to suppress warnings about unused variable x. But if I try compiling the following, I get some results I don't quite understand:
int main()
{
int x;
...
- 18.6k
77
votes
3
answers
37k
views
Can I get PyCharm to suppress a particular warning on a single line?
PyCharm provides some helpful warnings on code style, conventions and logical gotchas. It also provides a notification if I try to commit code with warnings (or errors).
Sometimes I consciously ...
- 16.1k
76
votes
9
answers
108k
views
How can I hide "defined but not used" warnings in GCC?
I have a bunch of compile time asserts, such as:
CASSERT(isTrue) or CASSERT2(isTrue, prefix_)
When compiling with GCC I get many warnings like 'prefix_LineNumber' defined but not used. Is there a ...
user34537
75
votes
5
answers
32k
views
Disable warnings in Xcode from frameworks
I have imported the three20 project into my project, and when I upgraded to Xcode 4.2 with iOS 5, a bunch of warnings appeared in the project.
I don't care about them, but they make a lot of noise, ...
- 14.4k
73
votes
6
answers
21k
views
What's up with the thousands of warnings in standard headers in MSVC -Wall?
Some people seem to advise you use -Wall, but when I did it on a small test project which just has a main.cpp with some includes, I get 5800 warnings most of them in standard headers or in windows ...
user1115652
70
votes
5
answers
114k
views
Unnecessary @SuppressWarnings("unused")
I'm getting a compiler warning for the @SuppressWarnings annotation in eclipse for the code:
@Override
public boolean doSomething(@SuppressWarnings("unused") String whatever) throws AnException {
...
- 8,510
69
votes
7
answers
142k
views
c array - warning: format not a string literal
I'm attempting to learn C and already I've run into an issue. I assume its trivial but I need to know it. I have written:
#include <stdio.h>
#include <string.h>
int main()
{
char ...
- 1,073
68
votes
7
answers
51k
views
Can GCC not complain about undefined references?
Under what situation is it possible for GCC to not throw an "undefined reference" link error message when trying to call made-up functions?
For example, a situation in which this C code is compiled ...
- 1,077
66
votes
8
answers
47k
views
Using enum inside types - Compiler warning C4482 C++
I am using fully qualified name of the enum inside a method in one of my class. But I am getting compiler warning which says "warning C4482: nonstandard extension used: enum 'Foo' used in qualified ...
- 15.4k
64
votes
3
answers
11k
views
C#: Is pragma warning restore needed?
From msdn I get this:
#pragma warning disable warning-list
#pragma warning restore warning-list
In the examples, both disable and restore are used. Is it necessary to restore if I want it disabled ...
- 155k
62
votes
3
answers
50k
views
How to ignore compiler warning when using Obsolete attribute on a class used with a KnownType attribute
So we are trying to deprecate some of our existing classes, and have started marking them as obsolete with the ObsoleteAttribute so they will stop being used. The fact that using the KnownType ...
- 4,990
62
votes
7
answers
84k
views
Avoid warning 'Unreferenced Formal Parameter'
I have a super class like this:
class Parent
{
public:
virtual void Function(int param);
};
void Parent::Function(int param)
{
std::cout << param << std::endl;
}
..and a sub-...
- 22.2k
61
votes
3
answers
165k
views
Compiler warning - suggest parentheses around assignment used as truth value
When I try to compile the piece of code below, I get this warning:
warning: suggest parentheses around assignment used as truth value
Why does this happen? This is a rather common idiom, I believe. ...
- 5,048
61
votes
10
answers
60k
views
assert() with message
I saw somewhere assert used with a message in the following way:
assert(("message", condition));
This seems to work great, except that gcc throws the following warning:
warning: left-hand operand ...
- 25.5k
61
votes
9
answers
90k
views
How can I suppress javac warnings about deprecated api?
When I compile, javac outputs:
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.`
I wish to suppress this warning. Trying -Xlint:none does ...
- 28.7k
61
votes
4
answers
31k
views
Why does C++ code missing a formal argument name in a function definition compile without warnings?
While getting started with some VS2005-generated MFC code, I noticed it overrode a method with something like this:
void OnDraw(CDC* /*pDC*/)
{
...
// TODO: Add your code here
}
So of course,...
- 10.2k
60
votes
5
answers
19k
views
C++ Force compile-time error/warning on implicit fall-through in switch
switch statements can be super useful, but lead to a common bug where a programmer forgot a break statement:
switch(val) {
case 0:
foo();
break;
case 1:
bar();
...
- 293k
59
votes
6
answers
150k
views
Multi-character constant warnings
Why is this a warning? I think there are many cases when is more clear to use multi-char int constants instead of "no meaning" numbers or instead of defining const variables with same value. When ...
- 20.5k
56
votes
8
answers
58k
views
Checking the gcc version in a Makefile?
I would like to use some gcc warning switchs that aren't available in older gcc versions (eg. -Wtype-limits).
Is there an easy way to check the gcc version and only add those extra options if a ...
- 5,299
56
votes
4
answers
30k
views
Is it wise to ignore gcc/clang's "-Wmissing-braces" warning?
Consider the following program:
#include <array>
int main()
{
std::array<int, 1> x = { 0 }; // warning!
x = { { 0 } }; // no warning
return 0;
}
The first initialization leads to ...
- 42.7k
55
votes
6
answers
26k
views
Why is there a performance warning on casting pointer to bool?
This question extends Why use !! when converting int to bool?.
I thought I was being cool when I did something like:
bool hasParent() {
return this->parentNode;
}
Where this->parentNode is ...
- 66.1k
54
votes
4
answers
17k
views
How to eliminate warning about ambiguity?
I have this warning:
Warning 3 Ambiguity between method 'Microsoft.Office.Interop.Word._Application.Quit(ref object, ref object, ref object)' and non-method 'Microsoft.Office.Interop.Word....
- 2,922
53
votes
1
answer
44k
views
How to get Intellij Idea to display compilation warnings?
I'm working with Intellij Idea 10 and Java 6 JDK Update 7. When I run Build --> Rebuild Project command, and the (javac) compilation generates warnings, Idea doesn't display what those warnings ...
- 8,570