Fix Cdist - Preserve dimensions when casting a vector to double

[mardukbp]

Using FastR release 19.2.0.1 the following code

m <- matrix(c(1L,2L,3L,4L,5L,6L), nrow=3, ncol=2)
dist(m)

results in Error: 'x' must be a square matrix.

The R function dist calls the C function Cdist defined in stats/src/distance.c. This function does not check whether its first argument is a matrix, but it checks the type of its elements:

if(TYPEOF(x) != REALSXP) x = coerceVector(x, REALSXP);

FastR implements the Java function Cdist, which checks whether its first argument is a matrix--not a square matrix--and if the test fails it throws

error(Message.MUST_BE_SQUARE_MATRIX, "x")

Throwing this error is wrong, because it does not correspond to the test that failed and because R's Cdist works for rectangular matrices. The Message enum is defined in RError.java.

The problem is that the argument x is casted to double without preserving its dimensions, resulting in a 1D vector. This patch corrects this.

To try it make clean in com.oracle.truffle.r.native and run mx buildon the project root.

I suspect that this mistake in casting vectors to double without preserving their dimensions occurs in other places in FastR.

[steve-s]

Hello Marduk,

thank you for your PR and thorough description. The PR looks good but could you also add a test with the code snippet that was not working before (or more misbehaving snippets if you have more)? The tests are located here: https://github.com/oracle/fastr/blob/master/com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/library/base/TestSimpleArithmetic.java. edit: I meant com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/library/stats and looking at that package, it seems we have no tests for Cdist yet..