16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
92 lines
2.0 KiB
Plaintext
92 lines
2.0 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 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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