special handling when %>% comes before conditional

Author: lorenzwalthert

NEWS.md

@@ -54,6 +54,9 @@
 
 ## Minor changes and fixes
 
+* No curly braces are added to else statements if they are within a pipe, as 
+  this can change evaluation logic of code involving the magrittr dot in rare 
+  cases (#816).
 * line breaks between `}` and `else` are removed (#793).
 * styler won't format code chunks with explicit `tidy = FALSE` in an Rmd or Rnw 
   code header anymore. This can be handy when the code can't be parsed, e.g.

R/rules-tokens.R

@@ -113,7 +113,8 @@ wrap_else_multiline_curly <- function(pd, indent_by = 2, space_after = 0) {
   if (contains_else_expr(pd) &&
     pd_is_multi_line(pd) &&
     contains_else_expr_that_needs_braces(pd) &&
-    !any(pd$stylerignore)) {
+    !any(pd$stylerignore) &&
+    pd$token_before[1] != "SPECIAL-PIPE") {
     else_idx <- which(pd$token == "ELSE")
     pd$spaces[else_idx] <- 1L
     all_to_be_wrapped_ind <- seq2(else_idx + 1L, nrow(pd))

tests/testthat/test-token_adding_removing.R

@@ -36,3 +36,10 @@ test_that("braces only added to pipe if RHS is a symbol", {
     transformer = style_text
   ), NA)
 })
+
+
+test_that("No braces are added if conditional statement is within pipe", {
+  expect_warning(test_collection("token_adding_removing", "else-pipe",
+    transformer = style_text
+  ), NA)
+})

tests/testthat/token_adding_removing/else-pipe-in.R

@@ -0,0 +1,9 @@
+mtcars %>%
+  mutate(
+    x = 1
+  ) %>%
+  if (FALSE) {
+    mutate(., country = 2)
+  } else .
+
+# adding braces around . in else changes evaluation

tests/testthat/token_adding_removing/else-pipe-in_tree

@@ -0,0 +1,9 @@
+mtcars %>%
+  mutate(
+    x = 1
+  ) %>%
+  if (FALSE) {
+    mutate(., country = 2)
+  } else .
+
+# adding braces around . in else changes evaluation