From 75e4e70ce4d72dc305d3ec09de2be2b1f923ae9c Mon Sep 17 00:00:00 2001
From: Sebastian <versat@users.noreply.github.com>
Date: Tue, 8 Oct 2019 10:55:40 +0200
Subject: [PATCH] Fix #9299 (Makefile: tools/matchcompiler.py is executed via
 Python 2) (#2247)

Check if "python" is available, if not check for "python3" and use
the available Python interpreter. If no Python interpreter is found,
"make" fails with an according error message.
This solves the issue that not all modern Linux distributions any longer
install Python 2 by default, so "python" is not available and
"make MATCHCOMPILER=yes" would fail. Instead of forcing the users to
install Python 2, Python 3 is used in such a case now if it is
available.
---
 Makefile        | 12 ++++++++++--
 tools/dmake.cpp | 12 ++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index a83dc89f5..613433682 100644
--- a/Makefile
+++ b/Makefile
@@ -19,10 +19,18 @@ ifeq ($(SRCDIR),build)
     MATCHCOMPILER:=yes
 endif
 ifeq ($(MATCHCOMPILER),yes)
+    # Find available Python interpreter
+    PYTHON_INTERPRETER := $(shell which python)
+    ifndef PYTHON_INTERPRETER
+        PYTHON_INTERPRETER := $(shell which python3)
+    endif
+    ifndef PYTHON_INTERPRETER
+        $(error Did not find a Python interpreter)
+    endif
     ifdef VERIFY
-        matchcompiler_S := $(shell python tools/matchcompiler.py --verify)
+        matchcompiler_S := $(shell $(PYTHON_INTERPRETER) tools/matchcompiler.py --verify)
     else
-        matchcompiler_S := $(shell python tools/matchcompiler.py)
+        matchcompiler_S := $(shell $(PYTHON_INTERPRETER) tools/matchcompiler.py)
     endif
     libcppdir:=build
 else
diff --git a/tools/dmake.cpp b/tools/dmake.cpp
index d700c4272..d786cee48 100644
--- a/tools/dmake.cpp
+++ b/tools/dmake.cpp
@@ -231,10 +231,18 @@ int main(int argc, char **argv)
          << "    MATCHCOMPILER:=yes\n"
          << "endif\n";
     fout << "ifeq ($(MATCHCOMPILER),yes)\n"
+         << "    # Find available Python interpreter\n"
+         << "    PYTHON_INTERPRETER := $(shell which python)\n"
+         << "    ifndef PYTHON_INTERPRETER\n"
+         << "        PYTHON_INTERPRETER := $(shell which python3)\n"
+         << "    endif\n"
+         << "    ifndef PYTHON_INTERPRETER\n"
+         << "        $(error Did not find a Python interpreter)\n"
+         << "    endif\n"
          << "    ifdef VERIFY\n"
-         << "        matchcompiler_S := $(shell python tools/matchcompiler.py --verify)\n"
+         << "        matchcompiler_S := $(shell $(PYTHON_INTERPRETER) tools/matchcompiler.py --verify)\n"
          << "    else\n"
-         << "        matchcompiler_S := $(shell python tools/matchcompiler.py)\n"
+         << "        matchcompiler_S := $(shell $(PYTHON_INTERPRETER) tools/matchcompiler.py)\n"
          << "    endif\n"
          << "    libcppdir:=build\n"
          << "else\n"