Add conf-protoc-dev virtual conf package

conf-protoc-dev.opam

@@ -0,0 +1,38 @@
+opam-version: "2.0"
+maintainer: "Anders Fugmann"
+authors: "Google"
+license: "BSD-3-Clause"
+homepage: "https://developers.google.com/protocol-buffers/"
+bug-reports: "https://github.com/protocolbuffers/protobuf/issues"
+dev-repo: "git+https://github.com/protocolbuffers/protobuf.git"
+build: [ make ]
+
+depends: [
+  "conf-pkg-config"
+]
+
+depexts: [
+  ["libprotoc-dev"]       {os-family = "debian"}
+  ["libprotoc-dev"]       {os-family = "ubuntu"}
+  ["lib64protobuf-devel"] {os-distribution = "mageia"}
+  ["protobuf-devel"]      {os-distribution = "centos"}
+  ["protobuf-devel"]      {os-distribution = "fedora"}
+  ["protobuf-devel"]      {os-distribution = "rhel"}
+  ["protobuf-dev"]        {os-family = "alpine"}
+  ["protobuf"]            {os-family = "arch"}
+  ["protobuf-devel"]      {os-family = "suse"}
+  ["protobuf"]            {os = "freebsd"}
+  ["protobuf"]            {os = "macos" & os-distribution = "homebrew"}
+]
+
+x-ci-accept-failures: [
+  "oraclelinux-7" # Package not available by default
+  "oraclelinux-8" # Package not available by default
+  "oraclelinux-9" # Package not available by default
+]
+
+available: (os-distribution != "ubuntu" | os-version >= "18.04") & (os-distribution != "centos" | os-version >= "8")
+synopsis: "Virtual package to install protobuf cpp headers"
+description:
+  "This package will install c header files and libaries for google protocol buffers via `opam depext`"
+flags: conf

files/Makefile

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+build:
+	c++ `pkg-config protobuf --cflags` -c -o test.o test.c

files/test.c

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+#include <google/protobuf/compiler/importer.h>