From 91cf8f3c6d500a5da69a19673704939b6e827e68 Mon Sep 17 00:00:00 2001
From: Dirk Eddelbuettel <edd@debian.org>
Date: Fri, 13 May 2016 14:03:33 -0500
Subject: [PATCH] first crack at checking compiler versions from R

currently limited to g++
---
 DESCRIPTION          |  1 +
 R/compilerCheck.R    | 36 ++++++++++++++++++++++++++++++++++++
 man/compilerCheck.Rd | 31 +++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100644 R/compilerCheck.R
 create mode 100644 man/compilerCheck.Rd

diff --git a/DESCRIPTION b/DESCRIPTION
index e0c8eda63..514f6afa6 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -21,3 +21,4 @@ URL: http://www.rcpp.org, http://dirk.eddelbuettel.com/code/rcpp.html, https://g
 License: GPL (>= 2)
 BugReports: https://github.com/RcppCore/Rcpp/issues
 MailingList: Please send questions and comments regarding Rcpp to rcpp-devel@lists.r-forge.r-project.org
+RoxygenNote: 5.0.1
diff --git a/R/compilerCheck.R b/R/compilerCheck.R
new file mode 100644
index 000000000..1db4331cf
--- /dev/null
+++ b/R/compilerCheck.R
@@ -0,0 +1,36 @@
+##' Helper function to establish minimal compiler versions, currently limited
+##' only to \code{g++} which (particularly for older RHEL/CentOS releases) is
+##' too far behind current C++11 standards required for some packages.
+##'
+##' This function looks up \code{g++} (as well as optional values in the
+##' \code{CXX} and \code{CXX1X} environment variables) in the \code{PATH}.  For
+##' all values found, the output of \code{g++ -v} is analyzed for the version
+##' string, which is then compared to the given minimal version.
+##' @title Check for Minimal (g++) Compiler Version
+##' @param minVersion An object of type \code{package_version}, with a default
+##'  of version 4.6.0
+##' @return A boolean value is returned, indicating if the minimal version is
+##'  being met
+##' @author Dirk Eddelbuettel
+compilerCheck <- function(minVersion=package_version("4.6.0")) {
+
+    binaries <- c("g++", Sys.getenv("CXX", unset=""), Sys.getenv("CXX1X", unset=""))
+    binpaths <- lapply(binaries, function(b) { if (b=="") NULL else Sys.which(b) })
+                       
+    allgood <- FALSE
+    rl <- lapply(binpaths, function(b) {
+        if (is.null(b)) return(NULL)
+        con <- pipe(paste(b, "-v 2>&1"), "r") # NB: not --version, but -v
+        lines <- readLines(con)
+        close(con)
+        lines <- lines[grepl("^g.. version", lines)]
+        if (length(lines) == 0) return(NULL)
+        ver <- strsplit(lines, " ")[[1]][3]   # format is 'gcc version x.y.z ....'
+        package_version(ver) >= minVersion
+    })
+    all(do.call(c, rl))                 # drops NULLs
+}
+
+## TODO: maybe not limit to gcc/g++
+## TODO: maybe be smarter about combination of path, CXX and CXX1X ?
+## TODO: maybe make env.var optional arguments too
diff --git a/man/compilerCheck.Rd b/man/compilerCheck.Rd
new file mode 100644
index 000000000..954ac883b
--- /dev/null
+++ b/man/compilerCheck.Rd
@@ -0,0 +1,31 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/compilerCheck.R
+\name{compilerCheck}
+\alias{compilerCheck}
+\title{Check for Minimal (g++) Compiler Version}
+\usage{
+compilerCheck(minVersion = package_version("4.6.0"))
+}
+\arguments{
+\item{minVersion}{An object of type \code{package_version}, with a default
+of version 4.6.0}
+}
+\value{
+A boolean value is returned, indicating if the minimal version is
+ being met
+}
+\description{
+Helper function to establish minimal compiler versions, currently limited
+only to \code{g++} which (particularly for older RHEL/CentOS releases) is
+too far behind current C++11 standards required for some packages.
+}
+\details{
+This function looks up \code{g++} (as well as optional values in the
+\code{CXX} and \code{CXX1X} environment variables) in the \code{PATH}.  For
+all values found, the output of \code{g++ -v} is analyzed for the version
+string, which is then compared to the given minimal version.
+}
+\author{
+Dirk Eddelbuettel
+}
+