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RFE: issue (optional) warning when '==' is used on wrapper types #2176

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dashorst opened this issue Mar 18, 2024 · 5 comments · May be fixed by #2188
Open

RFE: issue (optional) warning when '==' is used on wrapper types #2176

dashorst opened this issue Mar 18, 2024 · 5 comments · May be fixed by #2188
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enhancement New feature or request help wanted Extra attention is needed

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@dashorst
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dashorst commented Mar 18, 2024 •
edited

I would like that Eclipse (similar to IDEA) would issue an optional warning when one uses the following construct:

Long x1 = 12345L;
Long x2 = 67890L;
if(x1 == x2)
    System.out.println("Equal");
else
    System.out.println("Not equal");

Because (as apparently we don't all know) Long is a wrapper class and using == only works for Long values between -127 and 127 due to caching (similarly for the other wrapper types).

This would at least uncover one such instance in our code base, of which I suspect to find a greater number alas.
@iloveeclipse iloveeclipse added enhancement New feature or request needinfo Further information is requested labels Mar 18, 2024
@iloveeclipse
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iloveeclipse commented Mar 18, 2024 •
edited

What does javac report?
Note, static code analysis of semantically correct and compilable code is not necessarily what compiler is supposed to do.

@dashorst dashorst changed the title RFE: issue warning when '==' is used on wrapper types RFE: issue (optional) warning when '==' is used on wrapper types Mar 18, 2024
@dashorst
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While I sympathise with the "don't bloat the compiler with too much work" (that would make it slower etc), I doubt that the ECJ "Method can be static" optional problem is something a compiler should do as well, but causes fewer programming errors.

In any case, javac (17) doesn't issue a warning for either using == on Longs nor Strings.

I don't propose to emit a warning always, but make it an option similar to x == x (which isn't flagged by javac either).

@iloveeclipse iloveeclipse added help wanted Extra attention is needed and removed needinfo Further information is requested labels Mar 18, 2024
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I don't propose to emit a warning always, but make it an option similar to x == x (which isn't flagged by javac either).

Sure. If you (or anyone else) is interested to provide this feature, feel free to contribute.

dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 20, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
7ace56a 
When comparing wrapper types or Strings using '==' this is done by reference instead of value.
Usually this is in error (e.g. Long only caches values between -127 and +127). By flagging this
as an optional warning or even error (configurable) these cases can be easily weeded out.

Fixes eclipse-jdt#2176
@dashorst dashorst linked a pull request Mar 20, 2024 that will close this issue
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3 tasks
dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 20, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
10c5626 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 20, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
7ee8ffe 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 20, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
cfade8f 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
@dashorst
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Well, here you go!

dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 20, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
a4c9107 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Mar 27, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
dba7390 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
@dashorst
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The PR builds correctly, I'd love some feedback on whether it is complete, hits the correct spots and suitability for adoption.

stephan-herrmann pushed a commit to dashorst/eclipse.jdt.core that referenced this issue Apr 1, 2024
@dashorst @stephan-herrmann
feat: issue optional warning using '==' for wrapper types
014ee74 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
dashorst added a commit to dashorst/eclipse.jdt.core that referenced this issue Apr 2, 2024
@dashorst
feat: issue optional warning using '==' for wrapper types
be4d139 
When comparing wrapper types or Strings using '==' this is done by
reference instead of value. Usually this is in error (e.g. Long only
caches values between -127 and +127). By flagging this as an optional
warning or even error (configurable) these cases can be easily weeded
out.

Fixes eclipse-jdt#2176
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feat: issue optional warning using '==' for wrapper types dashorst/eclipse.jdt.core
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