Comparison of identical values¶
ID: go/comparison-of-identical-expressions Kind: problem Security severity: Severity: warning Precision: very-high Tags: - quality - reliability - correctness - external/cwe/cwe-570 - external/cwe/cwe-571 Query suites: - go-code-quality.qls - go-security-and-quality.qls Click to see the query in the CodeQL repository
Comparing two identical expressions typically indicates a mistake such as a missing qualifier or a misspelled variable name.
Recommendation¶
Carefully inspect the comparison to determine whether it is a symptom of a bug.
Example¶
In the example below, the method Rectangle.contains is intended to check whether a point (x, y) lies inside a rectangle r given by its origin (r.x, r.y), its width r.width, and its height r.height.
package main type Rectangle struct { x, y, width, height float64 } func (r *Rectangle) containsBad(x, y float64) bool { return r.x <= x && y <= y && x <= r.x+r.width && y <= r.y+r.height } Note, however, that on line 9 the programmer forgot to qualify r.y, thus ending up comparing the argument y against itself. The comparison should be fixed accordingly:
package main func (r *Rectangle) containsGood(x, y float64) bool { return r.x <= x && r.y <= y && x <= r.x+r.width && y <= r.y+r.height }