more vestigial code from allowing R<3.6 (#2289)

R/get_source_expressions.R

@@ -68,8 +68,7 @@ get_source_expressions <- function(filename, lines = NULL) {
   }
 
   # Only regard explicit attribute terminal_newline=FALSE as FALSE and all other cases (e.g. NULL or TRUE) as TRUE.
-  # We don't use isFALSE since it is introduced in R 3.5.0.
-  terminal_newline <- !identical(attr(source_expression$lines, "terminal_newline", exact = TRUE), FALSE)
+  terminal_newline <- !isFALSE(attr(source_expression$lines, "terminal_newline", exact = TRUE))
 
   e <- NULL
   source_expression$lines <- extract_r_source(
@@ -493,19 +492,6 @@ get_source_expression <- function(source_expression, error = identity) {
     error = error
   )
 
-  # TODO: Remove when minimum R version is bumped to > 3.5
-  #
-  # This needs to be done twice to avoid a bug fixed in R 3.4.4
-  #   https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16041
-  parsed_content <- tryCatch(
-    parse(
-      text = source_expression$content,
-      srcfile = source_expression,
-      keep.source = TRUE
-    ),
-    error = error
-  )
-
   if (inherits(parsed_content, c("error", "lint"))) {
     assign("e", parsed_content, envir = parent.frame())
     parse_error <- TRUE

R/namespace.R

@@ -85,13 +85,7 @@ is_s3_generic <- function(fun) {
 
 .base_s3_generics <- unique(c(
   names(.knownS3Generics),
-  if (getRversion() >= "3.5.0") {
-    .S3_methods_table[, 1L]
-  } else {
-    # R < 3.5.0 doesn't provide .S3_methods_table
-    # fallback: search baseenv() for generic methods
-    imported_s3_generics(data.frame(pkg = "base", fun = ls(baseenv()), stringsAsFactors = FALSE))$fun
-  },
+  .S3_methods_table[, 1L],
   # Contains S3 generic groups, see ?base::groupGeneric and src/library/base/R/zzz.R
   ls(.GenericArgsEnv)
 ))