From 91af010200b8abeeed7c2613a2c87c02b814ae0f Mon Sep 17 00:00:00 2001
From: Stefan Weil <sw@weilnetz.de>
Date: Tue, 1 Jan 2019 22:49:04 +0100
Subject: [PATCH] Fix compiler warning
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gcc warning:

    src/training/text2image.cpp:694:35: warning:
        ISO C++ forbids converting a string constant to ‘char*’
        [-Wwrite-strings]

putenv expects a string which can be modified.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 src/training/text2image.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/training/text2image.cpp b/src/training/text2image.cpp
index 43c1a96a48..bc4c73eafd 100644
--- a/src/training/text2image.cpp
+++ b/src/training/text2image.cpp
@@ -690,8 +690,9 @@ int main(int argc, char** argv) {
   // See https://github.com/tesseract-ocr/tesseract/issues/736
   char* backend;
   backend = getenv("PANGOCAIRO_BACKEND");
-  if (backend == NULL) {
-    putenv("PANGOCAIRO_BACKEND=fc");
+  if (backend == nullptr) {
+    static char envstring[] = "PANGOCAIRO_BACKEND=fc";
+    putenv(envstring);
   } else {
     printf("Using '%s' as pango cairo backend based on environment "
            "variable.\n", backend);