From 281d3d001ca8b44b5076fab3cdb9c2dac67c45e9 Mon Sep 17 00:00:00 2001
From: Marco Colombo <mar.colombo13@gmail.com>
Date: Sun, 11 Jan 2026 11:20:03 +0100
Subject: [PATCH 1/5] Report the LaTeX error from stderr when build_manual()
 fails.

This parses the stderr text for the "LaTeX Error:" line and reports it
if it's found.
---
 R/build-manual.R | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/R/build-manual.R b/R/build-manual.R
index 0c9112db2..4b041e50d 100644
--- a/R/build-manual.R
+++ b/R/build-manual.R
@@ -17,7 +17,10 @@ build_manual <- function(pkg = ".", path = NULL) {
   ), fail_on_status = TRUE, stderr = "2>&1", spinner = FALSE),
   error = function(e) {
     cat(e$stdout)
-    cli::cli_abort("Failed to build manual")
+    msg <- regmatches(e$stderr,
+                      regexpr("LaTeX Error:.*", e$stderr, perl = TRUE))
+    cli::cli_abort(c("x" = msg,
+                     "!" = "Failed to build manual"))
   })
 
   cat(msg$stdout)

From b54eafd40b08a587e3f1ac555e4fa254bd6f342a Mon Sep 17 00:00:00 2001
From: Marco Colombo <mar.colombo13@gmail.com>
Date: Mon, 12 Jan 2026 23:17:31 +0100
Subject: [PATCH 2/5] Print the entire stderr buffer in case of error.

---
 R/build-manual.R | 6 ++----
 R/utils.R        | 7 +++++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/R/build-manual.R b/R/build-manual.R
index 4b041e50d..923a703b1 100644
--- a/R/build-manual.R
+++ b/R/build-manual.R
@@ -14,12 +14,10 @@ build_manual <- function(pkg = ".", path = NULL) {
     "--force",
     paste0("--output=", path, "/", name),
     pkg$path
-  ), fail_on_status = TRUE, stderr = "2>&1", spinner = FALSE),
+  ), fail_on_status = TRUE, spinner = FALSE),
   error = function(e) {
     cat(e$stdout)
-    msg <- regmatches(e$stderr,
-                      regexpr("LaTeX Error:.*", e$stderr, perl = TRUE))
-    cli::cli_abort(c("x" = msg,
+    cli::cli_abort(c("x" = no_wrap(e$stderr),
                      "!" = "Failed to build manual"))
   })
 
diff --git a/R/utils.R b/R/utils.R
index 3ea06488a..105a2c7d1 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -44,3 +44,10 @@ is_testing <- function() {
 is_rstudio_running <- function() {
   !is_testing() && rstudioapi::isAvailable()
 }
+
+# Suppress cli wrapping
+no_wrap <- function(x) {
+  x <- gsub(" ", "\u00a0", x, fixed = TRUE)
+  x <- gsub("\n", "\f", x, fixed = TRUE)
+  x
+}

From 061b0bb0cb66d206fcf092d1023bdcc035064fb4 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Wed, 21 Jan 2026 11:15:25 -0600
Subject: [PATCH 3/5] Add basic test; polish `build_manual()`

---
 NEWS.md                               |  1 +
 R/build-manual.R                      | 25 ++++++++++++-------------
 tests/testthat/_snaps/build-manual.md | 11 +++++++++++
 tests/testthat/test-build-manual.R    | 19 +++++++++++++++++++
 4 files changed, 43 insertions(+), 13 deletions(-)
 create mode 100644 tests/testthat/_snaps/build-manual.md
 create mode 100644 tests/testthat/test-build-manual.R

diff --git a/NEWS.md b/NEWS.md
index 698c98a8d..2b5fb213c 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,6 @@
 # devtools (development version)
 
+* `build_manual()` reports more details on failure (#2586).
 * `is_loading()` is now re-exported from pkgload (#2556).
 * `load_all()` now errors if called recursively, i.e. if you accidentally include a `load_all()` call in one of your R source files (#2617).
 
diff --git a/R/build-manual.R b/R/build-manual.R
index 573fe2e23..452f0ecff 100644
--- a/R/build-manual.R
+++ b/R/build-manual.R
@@ -9,24 +9,23 @@
 build_manual <- function(pkg = ".", path = NULL) {
   pkg <- as.package(pkg)
   path <- path %||% path_dir(pkg$path)
-  name <- paste0(pkg$package, "_", pkg$version, ".pdf", collapse = " ")
+  name <- paste0(pkg$package, "_", pkg$version, ".pdf")
+  output <- file.path(path, name)
+
+  cli::cli_inform("Saving manual to {.file {output}}")
   tryCatch(
-    msg <- callr::rcmd(
+    invisible(callr::rcmd(
       "Rd2pdf",
-      cmdargs = c(
-        "--force",
-        paste0("--output=", path, "/", name),
-        pkg$path
-      ),
+      cmdargs = c("--force", paste0("--output=", output), pkg$path),
+      stdout = "",
       fail_on_status = TRUE,
       spinner = FALSE
-    ),
+    )),
     error = function(e) {
-      cat(e$stdout)
-      cli::cli_abort(c("x" = no_wrap(e$stderr), "!" = "Failed to build manual"))
+      cli::cli_abort(
+        c("Failed to build manual.", no_wrap(e$stderr)),
+        call = quote(build_manual())
+      )
     }
   )
-
-  cat(msg$stdout)
-  invisible(msg)
 }
diff --git a/tests/testthat/_snaps/build-manual.md b/tests/testthat/_snaps/build-manual.md
new file mode 100644
index 000000000..2bf08fd80
--- /dev/null
+++ b/tests/testthat/_snaps/build-manual.md
@@ -0,0 +1,11 @@
+# build_manual() shows stderr on failure
+
+    Code
+      build_manual(pkg)
+    Message
+      Saving manual to '<pkgdir>_0.0.0.9000.pdf'
+    Condition
+      Error in `build_manual()`:
+      ! Failed to build manual.
+      ! LaTeX Error: File `inconsolata.sty' not found.
+
diff --git a/tests/testthat/test-build-manual.R b/tests/testthat/test-build-manual.R
new file mode 100644
index 000000000..cdb24c106
--- /dev/null
+++ b/tests/testthat/test-build-manual.R
@@ -0,0 +1,19 @@
+test_that("build_manual() shows stderr on failure", {
+  pkg <- local_package_create()
+  pkg <- normalizePath(pkg)
+
+  # Create a mock error similar to what callr::rcmd produces
+  mock_error <- function(...) {
+  cnd <- rlang::error_cnd(
+      message = "System command 'R' failed",
+      stderr = "! LaTeX Error: File `inconsolata.sty' not found."
+    )
+    stop(cnd)
+  }
+  local_mocked_bindings(rcmd = mock_error, .package = "callr")
+
+  expect_snapshot(build_manual(pkg), error = TRUE, transform = function(x) {
+    x <- gsub(pkg, "<pkgdir>", x, fixed = TRUE)
+    x
+  })
+})

From d7ec69f04e9cefd6c7011fb9ed6b0d5d2995adf9 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Wed, 21 Jan 2026 11:32:57 -0600
Subject: [PATCH 4/5] More polishing

---
 R/build-manual.R                      | 23 ++++++++++++++---------
 tests/testthat/_snaps/build-manual.md |  2 ++
 tests/testthat/test-build-manual.R    | 14 +++++++-------
 3 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/R/build-manual.R b/R/build-manual.R
index 452f0ecff..301e773e3 100644
--- a/R/build-manual.R
+++ b/R/build-manual.R
@@ -13,19 +13,24 @@ build_manual <- function(pkg = ".", path = NULL) {
   output <- file.path(path, name)
 
   cli::cli_inform("Saving manual to {.file {output}}")
-  tryCatch(
-    invisible(callr::rcmd(
-      "Rd2pdf",
-      cmdargs = c("--force", paste0("--output=", output), pkg$path),
-      stdout = "",
-      fail_on_status = TRUE,
-      spinner = FALSE
-    )),
+  withCallingHandlers(
+    invisible(rd2pdf(pkg$path, output)),
     error = function(e) {
       cli::cli_abort(
         c("Failed to build manual.", no_wrap(e$stderr)),
-        call = quote(build_manual())
+        call = quote(build_manual()),
+        parent = e
       )
     }
   )
 }
+
+rd2pdf <- function(pkg_path, output_path) {
+  callr::rcmd(
+    "Rd2pdf",
+    cmdargs = c("--force", paste0("--output=", output_path), pkg_path),
+    stdout = "",
+    fail_on_status = TRUE,
+    spinner = FALSE
+  )
+}
diff --git a/tests/testthat/_snaps/build-manual.md b/tests/testthat/_snaps/build-manual.md
index 2bf08fd80..a8c212dd0 100644
--- a/tests/testthat/_snaps/build-manual.md
+++ b/tests/testthat/_snaps/build-manual.md
@@ -8,4 +8,6 @@
       Error in `build_manual()`:
       ! Failed to build manual.
       ! LaTeX Error: File `inconsolata.sty' not found.
+      Caused by error in `rd2pdf()`:
+      ! System command 'R' failed
 
diff --git a/tests/testthat/test-build-manual.R b/tests/testthat/test-build-manual.R
index cdb24c106..39bf4aaab 100644
--- a/tests/testthat/test-build-manual.R
+++ b/tests/testthat/test-build-manual.R
@@ -1,16 +1,16 @@
 test_that("build_manual() shows stderr on failure", {
+  skip_on_os("windows")
+
   pkg <- local_package_create()
   pkg <- normalizePath(pkg)
 
-  # Create a mock error similar to what callr::rcmd produces
-  mock_error <- function(...) {
-  cnd <- rlang::error_cnd(
-      message = "System command 'R' failed",
+  # Too hard to replicate actual error, so we just simulate
+  local_mocked_bindings(rd2pdf = function(...) {
+    rlang::abort(
+      "System command 'R' failed",
       stderr = "! LaTeX Error: File `inconsolata.sty' not found."
     )
-    stop(cnd)
-  }
-  local_mocked_bindings(rcmd = mock_error, .package = "callr")
+  })
 
   expect_snapshot(build_manual(pkg), error = TRUE, transform = function(x) {
     x <- gsub(pkg, "<pkgdir>", x, fixed = TRUE)

From 64101c68db1bcbd1d5a5ffd8922fcd9fd4daf3d3 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Wed, 21 Jan 2026 12:32:45 -0600
Subject: [PATCH 5/5] Silence the lint

---
 tests/testthat/test-build-manual.R | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tests/testthat/test-build-manual.R b/tests/testthat/test-build-manual.R
index 39bf4aaab..75b64e7ae 100644
--- a/tests/testthat/test-build-manual.R
+++ b/tests/testthat/test-build-manual.R
@@ -6,10 +6,8 @@ test_that("build_manual() shows stderr on failure", {
 
   # Too hard to replicate actual error, so we just simulate
   local_mocked_bindings(rd2pdf = function(...) {
-    rlang::abort(
-      "System command 'R' failed",
-      stderr = "! LaTeX Error: File `inconsolata.sty' not found."
-    )
+    stderr <- "! LaTeX Error: File `inconsolata.sty' not found."
+    rlang::abort("System command 'R' failed", stderr = stderr) #nolint
   })
 
   expect_snapshot(build_manual(pkg), error = TRUE, transform = function(x) {