From 8bbf1d9ab648f002a3c27f6735843273abdff457 Mon Sep 17 00:00:00 2001
From: Claus Hunsen <hunsen@fim.uni-passau.de>
Date: Tue, 28 Aug 2018 12:06:12 +0200
Subject: [PATCH] Fix finding of CXX prefix

When configuring the package, the finding of the correct CXX prefix is
crucial (see the file 'tools/config/configure.R'). As the function call
'read_r_config' (and, thus, 'R CMD config') does not return 'NULL' (but
an error message) if a constant is not configured, the wrong prefix is
chosen. This results in compilation errors.

To fix this problem, it needs to be checked whether the call to
'read_r_config' returns an error messsage or not.

Additionally, remove trailing whitespace in 'tools/config/configure.R'.

Signed-off-by: Claus Hunsen <hunsen@fim.uni-passau.de>
Signed-off-by: Thomas Bock <bockthom@fim.uni-passau.de>
---
 tools/config/configure.R | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/config/configure.R b/tools/config/configure.R
index b9313686..62c3556f 100644
--- a/tools/config/configure.R
+++ b/tools/config/configure.R
@@ -6,7 +6,7 @@ candidates <- c("CXX11", "CXX1X", "CXX")
 for (candidate in candidates) {
    config <- read_r_config(candidate, envir = NULL)
    value <- config[[candidate]]
-   if (!is.null(value)) {
+   if (!is.null(value) && !(startsWith(value, "ERROR:"))) {
       cxx <- candidate
       break
    }
@@ -26,7 +26,7 @@ if (broken)
 # configuration of R
 switch(
    cxx,
-   
+
    CXX11 = define(
       CC            = "$(CC)",
       CXX11         = "$(CXX11)",
@@ -34,7 +34,7 @@ switch(
       CXX11STD      = "$(CXX11STD)",
       CXX11PICFLAGS = "$(CXX11PICFLAGS)"
    ),
-   
+
    CXX1X = define(
       CC            = "$(CC)",
       CXX11         = "$(CXX1X)",
@@ -42,7 +42,7 @@ switch(
       CXX11STD      = "$(CXX1XSTD)",
       CXX11PICFLAGS = "$(CXX1XPICFLAGS)"
    ),
-   
+
    CXX = define(
       CC            = "$(CC)",
       CXX11         = "$(CXX)",
@@ -50,14 +50,14 @@ switch(
       CXX11STD      = "-std=c++0x",
       CXX11PICFLAGS = "-fPIC"
    ),
-   
+
    stop("Failed to infer C / C++ compilation flags")
 )
 
 # define special flags for Windows
 db <- configure_database()
 if (Sys.info()[["sysname"]] == "Windows") {
-   
+
    cygpath <- nzchar(Sys.which("cygpath"))
    fmt <- if (cygpath) "$(shell cygpath -m \"%s\")" else "%s"
    define(