Work around cmark sourcepos indent bug (#1391)

Closes #1353.

NEWS.md

@@ -1,5 +1,7 @@
 # roxygen2 (development version)
 
+* Fix bug interpolating the results of indented inline RMarkdown (#1353).
+
 * R6 documentation no longer shows inherited methods if there aren't any 
   (#1371).
 

R/markdown.R

@@ -71,10 +71,47 @@ markdown_pass1 <- function(text) {
   rcode_nodes <- keep(code_nodes, is_markdown_code_node)
   if (length(rcode_nodes) == 0) return(text)
   rcode_pos <- parse_md_pos(map_chr(rcode_nodes, xml_attr, "sourcepos"))
+  rcode_pos <- work_around_cmark_sourcepos_bug(text, rcode_pos)
   out <- eval_code_nodes(rcode_nodes)
   str_set_all_pos(text, rcode_pos, out, rcode_nodes)
 }
 
+# Work around commonmark sourcepos bug for inline R code
+# https://github.com/r-lib/roxygen2/issues/1353
+work_around_cmark_sourcepos_bug <- function(text, rcode_pos) {
+  if (Sys.getenv("ROXYGEN2_NO_SOURCEPOS_WORKAROUND", "") != "") {
+    return(rcode_pos)
+  }
+
+  lines <- str_split(text, fixed("\n"))[[1]]
+
+  for (l in seq_len(nrow(rcode_pos))) {
+    # Do not try to fix multi-line code, we error for that (below)
+    if (rcode_pos$start_line[l] != rcode_pos$end_line[l]) next
+    line <- lines[rcode_pos$start_line[l]]
+    start <- rcode_pos$start_column[l]
+
+    # Maybe correct? At some point this will be fixed upstream, hopefully.
+    if (str_sub(line, start - 1, start + 1) == "`r ") next
+
+    # Maybe indented and we can shift it?
+    # It is possible that the shift that we try accidentally matches
+    # "`r ", but it seems to be extremely unlikely. An example is this:
+    # #'       ``1`r `` `r 22*10`
+    # (seven spaces after the #', so an indent of six spaces. If we shift
+    # the real "`r " left by six characters, there happens to be another
+    # "`r " there.
+
+    indent <- nchar(str_extract(line, "^[ ]+"))
+    if (str_sub(line, start - 1 + indent, start + 1 + indent) == "`r ") {
+      rcode_pos$start_column[l] <- rcode_pos$start_column[l] + indent
+      rcode_pos$end_column[l] <- rcode_pos$end_column[l] + indent
+    }
+  }
+
+  rcode_pos
+}
+
 is_markdown_code_node <- function(x) {
   info <- str_sub(xml_attr(x, "info"), 1, 3)
   str_sub(xml_text(x), 1, 2) == "r " ||
@@ -124,8 +161,7 @@ knitr_chunk_defaults <- list(
 str_set_all_pos <- function(text, pos, value, nodes) {
   # Cmark has a bug when reporting source positions for multi-line
   # code tags, and it does not count the indenting space in the
-  # continuation lines. However, the bug might get fixed later, so
-  # for now we just simply error for multi-line inline code.
+  # continuation lines: https://github.com/commonmark/cmark/issues/296
   types <- xml_name(nodes)
   if (any(types == "code" & pos$start_line != pos$end_line)) {
     cli::cli_abort("multi-line `r ` markup is not supported", call = NULL)

tests/testthat/test-markdown-code.R

@@ -214,3 +214,19 @@ test_that("fragile tags in generated code", {
   expect_silent(out2 <- markdown("foo `r '\\\\out{<span></span>}'` bar"))
   expect_equal(out2, "foo \\out{<span></span>} bar")
 })
+
+test_that("workaround for cmark sourcepos bug (#1353) works", {
+  out <- roc_proc_text(rd_roclet(), "
+    #' Title
+    #'
+    #' line1
+    #'    pre `r \"1\"` 2 `r 1+2` post
+    #'
+    #' no workaround needed `r 'here'`
+    #' @md
+    foo <- function() {}
+  ")[[1]]
+
+  expect_equal(out$get_section("description")$value, "line1\npre 1 2 3 post")
+  expect_equal(out$get_section("details")$value, "no workaround needed here")
+})