Adress codex review

Author: mns-nordicals

R/r2f-matrix.R

@@ -632,12 +632,21 @@ register_r2f_handler(
   "diag",
   function(args, scope, ..., hoist = NULL, dest = NULL) {
     arg_names <- names(args)
-    has_first <- length(args) >= 1L
-    first_named <- has_first &&
-      length(arg_names) >= 1L &&
-      nzchar(arg_names[[1L]])
-    first_is_dim <- first_named && arg_names[[1L]] %in% c("nrow", "ncol")
-    x_arg <- if (!has_first || first_is_dim) NULL else args$x %||% args[[1L]]
+    if (is.null(arg_names)) {
+      arg_names <- rep("", length(args))
+    }
+    x_arg <- NULL
+    if (!is.null(args$x) && !is_missing(args$x)) {
+      x_arg <- args$x
+    } else if (length(args) >= 1L) {
+      unnamed_idx <- which(!nzchar(arg_names) | is.na(arg_names))
+      if (length(unnamed_idx) >= 1L) {
+        candidate <- args[[unnamed_idx[[1L]]]]
+        if (!is_missing(candidate)) {
+          x_arg <- candidate
+        }
+      }
+    }
     nrow_arg <- args$nrow
     ncol_arg <- args$ncol
     if (!is.null(args$names) && !is_missing(args$names)) {

tests/testthat/test-matrix-lapack.R

@@ -117,6 +117,11 @@ test_that("diag matches R for vectors, matrices, and sizes", {
     diag(x, nrow = 2, ncol = 3)
   }
 
+  diag_named_order <- function(x) {
+    declare(type(x = double(n)))
+    diag(nrow = 3L, x = x)
+  }
+
   set.seed(3)
   x <- rnorm(4)
   A <- matrix(rnorm(2 * 3), nrow = 2)
@@ -125,6 +130,7 @@ test_that("diag matches R for vectors, matrices, and sizes", {
   expect_quick_equal(diag_mat, list(A = A))
   expect_quick_equal(diag_size, list())
   expect_quick_equal(diag_value, list(x = 2.5))
+  expect_quick_equal(diag_named_order, list(x = c(1, 2)))
 })
 
 test_that("diag handles missing x with nrow/ncol and 1x1 matrices", {