mutate() doesn't seem to signal warning conditions properly

[jmbarbone]

mutate() doesn't seem to signal named warning conditions for calling handlers to pick up.

Example: function emits a custom condition, and that specific class can't be suppressed.

library(dplyr, warn.conflicts = FALSE)

foo_warn <- function(x) {
  warning(my_warning)
  x
}

my_warning <- structure(
  list(message = "MY_WARNING", call = NULL),
  class = c("my_warning", "warning", "condition")
)

df <- data.frame(x = 1, y = 2)

suppressWarnings(
  mutate(df, x = foo_warn(x)),
  "my_warning"
)
#> Warning: There was 1 warning in `mutate()`.
#> ℹ In argument: `x = foo_warn(x)`.
#> Caused by warning:
#> ! MY_WARNING
#>   x y
#> 1 1 2

# my_warningis never signaled, handlers can't pick it up
withCallingHandlers(
  mutate(df, x = foo_warn(x)),
  my_warning = function(c) {
    stop("condition signaled")
  }
)
#> Warning: There was 1 warning in `mutate()`.
#> ℹ In argument: `x = foo_warn(x)`.
#> Caused by warning:
#> ! MY_WARNING
#>   x y
#> 1 1 2

# but removing the `warning` class is at least a work-around
# 
foo_cond <- function(x) {
  warning(my_condition)
  x
}

my_condition <- structure(
  list(message = "MY_CONDITION", call = NULL),
  class = c("my_condition", "condition")
)

withCallingHandlers(
  mutate(df, x = foo_cond(x)),
  my_condition = function(c) {
    stop("condition signaled")
  }
)
#> Error in (function (c) : condition signaled

^{Created on 2025-02-20 with reprex v2.1.1}

[philibe]

And with warning parameter ?:

library(dplyr, warn.conflicts = FALSE)

foo_warn <- function(x) {
  warning(my_warning)
  x
}

my_warning <- structure(
  list(message = "MY_WARNING", call = NULL),
  class = c("my_warning", "warning", "condition")
)

df <- data.frame(x = 1, y = 2)


withCallingHandlers(
  mutate(df, x = foo_warn(x)),
  warning=function(w)  {
    print(w)
    stop("condition signaled")
  }, 
  error = function(e) {
    print(e)
    e
  }
)
#> <warning/rlang_warning>
#> Warning:
#> There was 1 warning in `mutate()`.
#> ℹ In argument: `x = foo_warn(x)`.
#> Caused by warning:
#> ! MY_WARNING
#> <simpleError in (function (w) {    print(w)    stop("condition signaled")})(structure(list(message = "There was 1 warning in `mutate()`.\nℹ In argument: `x = foo_warn(x)`.\nCaused by warning:\n! MY_WARNING",     parent = NULL, call = NULL, footer = character(0)), class = c("rlang_warning", "warning", "condition"))): condition signaled>
#> Error in (function (w) : condition signaled

withCallingHandlers(
  df,
  warning=function(w)  {
    print(w)
    stop("condition signaled")
  }, 
  error = function(e) {
    print(e)
    e
  }
)
#>   x y
#> 1 1 2

^{Created on 2025-02-21 with reprex v2.1.1}

[jmbarbone]

@philibe , the problem is that the my_warning class can't be specifically suppressed/captured. withCallingHandlers() can pick up on specific classes of conditions. withCallingHandlers() is sensitive to the order of ...,

library(dplyr, warn.conflicts = FALSE)

foo_warn <- function(x) {
  warning(my_warning)
  x
}

my_warning <- structure(
  list(message = "MY_WARNING", call = NULL),
  class = c("my_warning", "warning", "condition")
)

df <- data.frame(x = 1, y = 2)

# muffles any condition with a 'warning' class
suppressWarnings(
  mutate(df, x = foo_warn(x))
)
#>   x y
#> 1 1 2

# specificially tries to muffle 'my_warning' conditions
suppressWarnings(
  mutate(df, x = foo_warn(x)),
  "my_warning"
)
#> Warning: There was 1 warning in `mutate()`.
#> ℹ In argument: `x = foo_warn(x)`.
#> Caused by warning:
#> ! MY_WARNING
#>   x y
#> 1 1 2

# the 'my_warning' condition replaced with an 'rlang_warning' condition
tryCatch(
  mutate(df, x = foo_warn(x)),
  warning = str
)
#> List of 4
#>  $ message: chr "There was 1 warning in `mutate()`.\nℹ In argument: `x = foo_warn(x)`.\nCaused by warning:\n! MY_WARNING"
#>  $ parent : NULL
#>  $ call   : NULL
#>  $ footer : chr(0) 
#>  - attr(*, "class")= chr [1:3] "rlang_warning" "warning" "condition"

# order of the calling handlers is important
try(withCallingHandlers(
  foo_warn(1),
  my_warning = function(c) stop("'my_warning' hit"),
  warning = function(c) stop("'warning' hit")
))
#> Error in (function (c)  : 'my_warning' hit

try(withCallingHandlers(
  foo_warn(1),
  warning = function(c) stop("'warning' hit"),
  my_warning = function(c) stop("'my_warning' hit")
))
#> Error in (function (c)  : 'warning' hit

# 'rlang_warning' signaled before 'my_warning'
withCallingHandlers(
  mutate(df, x = foo_warn(x)),
  my_warning = function(c) stop("'my_warning' hit"),
  rlang_warning = function(c) stop("'rlang_warning' hit"),
  warning = function(c) stop("'warning' hit")
)
#> Error in (function (c) : 'rlang_warning' hit

^{Created on 2025-02-21 with reprex v2.1.1}