95 lines
2.2 KiB
Plaintext
95 lines
2.2 KiB
Plaintext
== Why is this an issue?
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include::../description.adoc[]
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=== Noncompliant code example
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[source,java]
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----
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if ( a == a ) { // always true
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doZ();
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}
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if ( a != a ) { // always false
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doY();
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}
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if ( a == b && a == b ) { // if the first one is true, the second one is too
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doX();
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}
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if ( a == b || a == b ) { // if the first one is true, the second one is too
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doW();
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}
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int j = 5 / 5; //always 1
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int k = 5 - 5; //always 0
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c.equals(c); //always true
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----
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=== Exceptions
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* This rule ignores ``++*++``, ``+``, and ``++=++``.
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* The specific case of testing a floating point value against itself is a valid test for ``++NaN++`` and is therefore ignored.
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* Similarly, left-shifting 1 onto 1 is common in the construction of bit masks, and is ignored.
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[source,java]
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----
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float f;
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if(f != f) { //test for NaN value
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System.out.println("f is NaN");
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}
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int i = 1 << 1; // Compliant
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int j = a << a; // Noncompliant
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----
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== Resources
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* https://wiki.sei.cmu.edu/confluence/x/5dUxBQ[CERT, MSC12-C.] - Detect and remove code that has no effect or is never executed
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* S1656 - Implements a check on ``++=++``.
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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include::../message.adoc[]
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include::../highlighting.adoc[]
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'''
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== Comments And Links
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(visible only on this page)
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=== on 21 Nov 2024, 16:48:00 Alban Auzeill wrote:
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[test-code-support-investigation-for-java] Decision for scope: Keep 'Main'. Tests do this to validate `equals`.
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=== on 1 Oct 2014, 11:39:51 Nicolas Peru wrote:
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Sub task for RSPEC-1764 with updated description for Java, please review.
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=== on 1 Oct 2014, 11:44:49 Ann Campbell wrote:
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\[~nicolas.peru] I question retaining this noncompliant example:
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----
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if (5 / 5) { // always 1
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doV();
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}
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----
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In C, >=1 evaluates to true & 0 evaluates to false. Is it that the same holds true in Java but it's just considered very bad form? If so, then why eliminate this one:
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----
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if (5 - 5) { // always 0
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do_u();
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}
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----
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?
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Also, we have a different rule that yells at people for using equality operators with floating-point numbers, so the first exception is doubly confusing
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include::../comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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