From d54d363a256a4f4d17830ef9d476a018104c35b7 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Wed, 7 Nov 2018 18:53:06 -0500
Subject: [PATCH] implement ConfigureOp#check_cxx_compiler

---
 build_tests/configure/check_cxx_compiler.rb   |  3 ++
 .../check_cxx_compiler_find_first.rb          |  3 ++
 lib/rscons/application.rb                     |  3 ++
 lib/rscons/configure_op.rb                    | 54 +++++++++++++++++++
 spec/build_tests_spec.rb                      | 34 ++++++++++++
 5 files changed, 97 insertions(+)
 create mode 100644 build_tests/configure/check_cxx_compiler.rb
 create mode 100644 build_tests/configure/check_cxx_compiler_find_first.rb

diff --git a/build_tests/configure/check_cxx_compiler.rb b/build_tests/configure/check_cxx_compiler.rb
new file mode 100644
index 0000000..56eb33e
--- /dev/null
+++ b/build_tests/configure/check_cxx_compiler.rb
@@ -0,0 +1,3 @@
+configure do
+  check_cxx_compiler
+end
diff --git a/build_tests/configure/check_cxx_compiler_find_first.rb b/build_tests/configure/check_cxx_compiler_find_first.rb
new file mode 100644
index 0000000..564c60f
--- /dev/null
+++ b/build_tests/configure/check_cxx_compiler_find_first.rb
@@ -0,0 +1,3 @@
+configure do
+  check_cxx_compiler "g++", "clang++"
+end
diff --git a/lib/rscons/application.rb b/lib/rscons/application.rb
index e7bad87..12e4a21 100644
--- a/lib/rscons/application.rb
+++ b/lib/rscons/application.rb
@@ -88,6 +88,9 @@ module Rscons
         if ccc = @script.check_c_compiler
           co.check_c_compiler(ccc)
         end
+        if ccc = @script.check_cxx_compiler
+          co.check_cxx_compiler(ccc)
+        end
       rescue ConfigureOp::ConfigureFailure
         rv = 1
       end
diff --git a/lib/rscons/configure_op.rb b/lib/rscons/configure_op.rb
index 8643421..0225e42 100644
--- a/lib/rscons/configure_op.rb
+++ b/lib/rscons/configure_op.rb
@@ -49,6 +49,29 @@ module Rscons
       end
     end
 
+    # Check for a working C++ compiler.
+    #
+    # @param ccc [Array<String>]
+    #   C++ compiler(s) to check for.
+    #
+    # @return [void]
+    def check_cxx_compiler(ccc)
+      $stdout.write("Checking for C++ compiler... ")
+      if ccc.empty?
+        # Default C++ compiler search array.
+        ccc = %w[g++ clang++]
+      end
+      cc = ccc.find do |cc|
+        test_cxx_compiler(cc)
+      end
+      if cc
+        Ansi.write($stdout, :green, cc, "\n")
+      else
+        Ansi.write($stdout, :red, "not found\n")
+        raise ConfigureFailure.new
+      end
+    end
+
     private
 
     # Test a C compiler.
@@ -81,6 +104,37 @@ module Rscons
       status == 0
     end
 
+    # Test a C++ compiler.
+    #
+    # @param cc [String]
+    #   C++ compiler to test.
+    #
+    # @return [Boolean]
+    #   Whether the C++ compiler tested successfully.
+    def test_cxx_compiler(cc)
+      File.open("#{@work_dir}/cfgtest.cxx", "wb") do |fh|
+        fh.puts <<-EOF
+          #include <iostream>
+          using namespace std;
+          int main(int argc, char * argv[]) {
+            cout << "Hello." << endl;
+            return 0;
+          }
+        EOF
+      end
+      case cc
+      when "g++"
+        command = %W[g++ -o #{@work_dir}/cfgtest.exe #{@work_dir}/cfgtest.cxx]
+      when "clang++"
+        command = %W[clang++ -o #{@work_dir}/cfgtest.exe #{@work_dir}/cfgtest.cxx]
+      else
+        $stderr.puts "Unknown C++ compiler (#{cc})"
+        raise ConfigureFailure.new
+      end
+      _, _, status = log_and_test_command(command)
+      status == 0
+    end
+
     # Execute a test command and log the result.
     def log_and_test_command(command)
       begin
diff --git a/spec/build_tests_spec.rb b/spec/build_tests_spec.rb
index 5fa0560..ddf9bb1 100644
--- a/spec/build_tests_spec.rb
+++ b/spec/build_tests_spec.rb
@@ -1534,6 +1534,40 @@ EOF
         end
       end
     end
+
+    context "check_cxx_compiler" do
+      {"check_cxx_compiler.rb" => "when no arguments are given",
+       "check_cxx_compiler_find_first.rb" => "when arguments are given"}.each_pair do |rsconsfile, desc|
+        context desc do
+          it "finds the first listed C++ compiler" do
+            test_dir "configure"
+            result = run_rscons(rsconsfile: rsconsfile, op: "configure")
+            expect(result.stderr).to eq ""
+            expect(result.status).to eq 0
+            expect(result.stdout).to match /Checking for C\+\+ compiler\.\.\. g\+\+/
+          end
+
+          it "finds the second listed C++ compiler" do
+            test_dir "configure"
+            create_exe "g++", "exit 1"
+            result = run_rscons(rsconsfile: rsconsfile, op: "configure")
+            expect(result.stderr).to eq ""
+            expect(result.status).to eq 0
+            expect(result.stdout).to match /Checking for C\+\+ compiler\.\.\. clang\+\+/
+          end
+
+          it "fails to configure when it cannot find a C++ compiler" do
+            test_dir "configure"
+            create_exe "g++", "exit 1"
+            create_exe "clang++", "exit 1"
+            result = run_rscons(rsconsfile: rsconsfile, op: "configure")
+            expect(result.stderr).to eq ""
+            expect(result.status).to_not eq 0
+            expect(result.stdout).to match /Checking for C\+\+ compiler\.\.\. not found/
+          end
+        end
+      end
+    end
   end
 
 end