Check duplicate names in sql_translator()

NEWS.md

@@ -1,5 +1,7 @@
 # dbplyr (development version)
 
+* `sql_translator()` now checks for duplicated definitions (@krlmlr, #1374).
+
 # dbplyr 2.4.0
 
 ## Breaking changes

R/backend-.R

@@ -140,7 +140,9 @@ base_scalar <- sql_translator(
     }
   },
   log10   = sql_prefix("LOG10", 1),
-  round   = sql_prefix("ROUND", 2),
+  round = function(x, digits = 0L) {
+    sql_expr(ROUND(!!x, !!as.integer(digits)))
+  },
   sign    = sql_prefix("SIGN", 1),
   sin     = sql_prefix("SIN", 1),
   sqrt    = sql_prefix("SQRT", 1),
@@ -152,10 +154,6 @@ base_scalar <- sql_translator(
   tanh     = function(x) sql_expr((!!sql_exp(2, x) - 1L) / (!!sql_exp(2, x) + 1L)),
   coth     = function(x) sql_expr((!!sql_exp(2, x) + 1L) / (!!sql_exp(2, x) - 1L)),
 
-  round = function(x, digits = 0L) {
-    sql_expr(ROUND(!!x, !!as.integer(digits)))
-  },
-
   `if` = function(cond, if_true, if_false = NULL) {
     sql_if(enquo(cond), enquo(if_true), enquo(if_false))
   },

R/translate-sql-helpers.R

@@ -124,6 +124,14 @@ sql_translator <- function(...,
   funs <- c(list2(...), .funs)
   if (length(funs) == 0) return(.parent)
 
+  if (anyDuplicated(names(funs))) {
+    bullets <- unique(names(funs)[duplicated(names(funs))])
+    cli_abort(c(
+      "Duplicate names in {.fun sql_translator}",
+      set_names(bullets, "*")
+    ))
+  }
+
   list2env(funs, copy_env(.parent))
 }
 

tests/testthat/_snaps/translate-sql-helpers.md

@@ -1,3 +1,12 @@
+# duplicates throw an error
+
+    Code
+      sql_translator(round = function(x) x, round = function(y) y)
+    Condition
+      Error in `sql_translator()`:
+      ! Duplicate names in `sql_translator()`
+      * round
+
 # output of print method for sql_variant is correct
 
     Code

tests/testthat/test-translate-sql-helpers.R

@@ -22,6 +22,12 @@ test_that("missing window functions create a warning", {
   )
 })
 
+test_that("duplicates throw an error", {
+  expect_snapshot(error = TRUE, {
+    sql_translator(round = function(x) x, round = function(y) y)
+  })
+})
+
 test_that("missing aggregate functions filled in", {
   local_con(simulate_dbi())
   sim_scalar <- sql_translator()