Fix leaf-function extraction dropping part of the label

pv_print_hot_paths() stripped the trailing " (file:line)" from a stack
entry with sub(" \\(.*\\)$", "", x). The greedy .* begins at the first
" (" in the string, so any label containing a space before an open paren
lost that part too:

  "if (x > 1) (file.R:3)"  ->  "if"

The truncated name then fed is_user_function() and the pv_focus(p, "...")
next-step suggestion, which could name a function that does not exist.

Extracted strip_location() into utils.R, anchored on the file:line shape,
which the location always has and a label never does.

Author: EmilHvitfeldt

R/hot-paths.R

@@ -118,7 +118,9 @@ pv_print_hot_paths <- function(x, n = 10, include_source = TRUE) {
     # Extract the leaf function from the hottest path (last in the chain)
     parts <- strsplit(paths$stack[1], " -> ")[[1]]
     # Remove source info if present: "func (file:line)" -> "func"
-    leaf_func <- sub(" \\(.*\\)$", "", parts[length(parts)])
+    # Anchor on the file:line shape rather than ".*", so labels that themselves
+    # contain " (" (e.g. "if (x > 1)") keep their parenthesised part.
+    leaf_func <- strip_location(parts[length(parts)])
     suggestions <- "pv_flame(p)"
     if (is_user_function(leaf_func)) {
       suggestions <- c(sprintf("pv_focus(p, \"%s\")", leaf_func), suggestions)

R/utils.R

@@ -140,6 +140,14 @@ cat_help_hint <- function() {
   cat("Run pv_help() to see all available functions.\n")
 }
 
+# Strip a trailing " (file:line)" suffix from a stack entry, leaving the label.
+# The location never contains spaces or parens and always ends in ":<digits>",
+# so anchoring on that shape is safe even when the label itself contains " (",
+# as in "if (x > 1) (file.R:3)". A greedy " \\(.*\\)$" would eat both parts.
+strip_location <- function(entry) {
+  sub(" \\([^ ()]+:[0-9]+\\)$", "", entry)
+}
+
 # Check if a function name is a user function (not internal R machinery)
 # Internal functions start with: ( like (top-level), < like <GC>, [ like [.data.frame
 is_user_function <- function(func_name) {

tests/testthat/test-utils.R

@@ -71,3 +71,14 @@ test_that("get_source_lines returns NULL when start > end after clamping", {
   result <- debrief:::get_source_lines("R/main.R", 10, 2, contents)
   expect_null(result)
 })
+
+test_that("strip_location keeps labels containing ' ('", {
+  expect_equal(strip_location("paste (analysis.R:22)"), "paste")
+  expect_equal(strip_location("if (x > 1) (file.R:3)"), "if (x > 1)")
+  expect_equal(
+    strip_location("data.frame(x = x, y = y) (analysis.R:11)"),
+    "data.frame(x = x, y = y)"
+  )
+  expect_equal(strip_location("plain_label"), "plain_label")
+  expect_equal(strip_location("f(a) (b)"), "f(a) (b)")
+})