Avoid R package warning in loadSupport() if autoload is disabled

NEWS.md

@@ -20,6 +20,8 @@
 
 * Calling `updateSelectizeInput()` with `choices` and `selected` now clears the current selection before updating the choices and selected value. (#3967)
 
+* Loading a Shiny app in a package-like directory will no longer warn if autoloading is disabled by the presence of an `R/_disable_autoload.R` file. (Thanks to @krlmlr and @tanho63, #3513)
+
 # shiny 1.8.0
 
 ## Breaking changes

R/shinyapp.R

@@ -351,17 +351,6 @@ loadSupport <- function(appDir=NULL, renv=new.env(parent=globalenv()), globalren
     appDir <- findEnclosingApp(".")
   }
 
-  descFile <- file.path.ci(appDir, "DESCRIPTION")
-  if (file.exists(file.path.ci(appDir, "NAMESPACE")) ||
-      (file.exists(descFile) &&
-       identical(as.character(read.dcf(descFile, fields = "Type")), "Package")))
-  {
-    warning(
-      "Loading R/ subdirectory for Shiny application, but this directory appears ",
-      "to contain an R package. Sourcing files in R/ may cause unexpected behavior."
-    )
-  }
-
   if (!is.null(globalrenv)){
     # Evaluate global.R, if it exists.
     globalPath <- file.path.ci(appDir, "global.R")
@@ -376,10 +365,12 @@ loadSupport <- function(appDir=NULL, renv=new.env(parent=globalenv()), globalren
   helpersDir <- file.path(appDir, "R")
 
   disabled <- list.files(helpersDir, pattern="^_disable_autoload\\.r$", recursive=FALSE, ignore.case=TRUE)
-  if (length(disabled) > 0){
+  if (length(disabled) > 0) {
     return(invisible(renv))
   }
 
+  warn_if_app_dir_is_package(appDir)
+
   helpers <- list.files(helpersDir, pattern="\\.[rR]$", recursive=FALSE, full.names=TRUE)
   # Ensure files in R/ are sorted according to the 'C' locale before sourcing.
   # This convention is based on the default for packages. For details, see:
@@ -394,6 +385,27 @@ loadSupport <- function(appDir=NULL, renv=new.env(parent=globalenv()), globalren
   invisible(renv)
 }
 
+warn_if_app_dir_is_package <- function(appDir) {
+  has_namespace <- file.exists(file.path.ci(appDir, "NAMESPACE"))
+  has_desc_pkg <- FALSE
+
+  if (!has_namespace) {
+    descFile <- file.path.ci(appDir, "DESCRIPTION")
+
+    has_desc_pkg <-
+      file.exists(descFile) &&
+      identical(as.character(read.dcf(descFile, fields = "Type")), "Package")
+  }
+
+  if (has_namespace || has_desc_pkg) {
+    warning(
+      "Loading R/ subdirectory for Shiny application, but this directory appears ",
+      "to contain an R package. Sourcing files in R/ may cause unexpected behavior. ",
+      "See `?loadSupport` for more details."
+    )
+  }
+}
+
 # This reads in an app dir for a single-file application (e.g. app.R), and
 # returns a shiny.appobj.
 # appDir must be a normalized (absolute) path, not a relative one