move pipe adder one level up so we have the context of the enclosing call and can check if it's substitute or not.

Note that this won't work if substitute itself is a placeholder (see issue)

Author: lorenzwalthert

NEWS.md

@@ -1,5 +1,7 @@
 # styler 1.6.2.9000 (Development version)
 
+* Piped function without brackets `substitute(x %>% y)` don't get `()` added
+  anymore, as this can change outcome of the code (#876).
 * Alignment detection respects stylerignore (#850).
 * Add vignette on distributing style guide (#846, #861).
 * Enable pre-commit.ci (#843).

R/rules-tokens.R

@@ -17,6 +17,13 @@ resolve_semicolon <- function(pd) {
 }
 
 add_brackets_in_pipe <- function(pd) {
+  if (!identical(pd$text[next_non_comment(pd, 0L)], "substitute")) {
+    pd$child <- map(pd$child, add_brackets_in_pipe_child)
+  }
+  pd
+}
+
+add_brackets_in_pipe_child <- function(pd) {
   is_pipe <- pd$token %in% c("SPECIAL-PIPE", "PIPE")
   Reduce(add_brackets_in_pipe_one, which(is_pipe), init = pd)
 }

tests/testthat/test-token_adding_removing.R

@@ -43,3 +43,9 @@ test_that("No braces are added if conditional statement is within pipe", {
     transformer = style_text
   ), NA)
 })
+
+test_that("No brace is added within `substitute()`", {
+  expect_warning(test_collection("token_adding_removing", "substitute",
+    transformer = style_text
+  ), NA)
+})

tests/testthat/token_adding_removing/substitute-in.R

@@ -0,0 +1,3 @@
+expr <- substitute(airquality %>% FUN_EXPR, env = list(FUN_EXPR = call("FUN_head")))
+a %>%
+  x

tests/testthat/token_adding_removing/substitute-in_tree

@@ -0,0 +1,3 @@
+expr <- substitute(airquality %>% FUN_EXPR, env = list(FUN_EXPR = call("FUN_head")))
+a %>%
+  x()