bind: reduce shared library count from 2 to 1 and use ABI version tagged extension

This merge replaces the python extension linked against the go shared library with a single python extension module. The extension module is also named using the ABI version tagging reported by the python configuration to avoid clashes with other python minor version builds.
Removes need/reference for LD_LIBRARY_PATH modification.

Fixes #249

Author: justinfx

README.md

@@ -177,7 +177,6 @@ package hi exposes a few Go functions to be wrapped and used from Python.
 ### From the command line
 
 ```sh
-$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:./
 $ gopy build -output=out -vm=`which python3` github.com/go-python/gopy/_examples/hi
 $ ls out
 Makefile  __init__.py  __pycache__/  _hi.so*  build.py  go.py  hi.c  hi.go  hi.py  hi_go.h  hi_go.so  patch-leaks.go

bind/utils.go

@@ -86,9 +86,10 @@ func isConstructor(sig *types.Signature) bool {
 }
 
 type PyConfig struct {
-	Version int
-	CFlags  string
-	LdFlags string
+	Version   int
+	CFlags    string
+	LdFlags   string
+	ExtSuffix string
 }
 
 // AllFlags returns CFlags + " " + LdFlags
@@ -114,6 +115,7 @@ if "GOPY_INCLUDE" in os.environ and "GOPY_LIBDIR" in os.environ and "GOPY_PYLIB"
 		"shlibs":  ds.get_config_var("SHLIBS"),
 		"syslibs": ds.get_config_var("SYSLIBS"),
 		"shlinks": ds.get_config_var("LINKFORSHARED"),
+		"extsuffix": ds.get_config_var("EXT_SUFFIX"),
 }))
 else:
 	print(json.dumps({
@@ -124,6 +126,7 @@ else:
 		"shlibs":  ds.get_config_var("SHLIBS"),
 		"syslibs": ds.get_config_var("SYSLIBS"),
 		"shlinks": ds.get_config_var("LINKFORSHARED"),
+		"extsuffix": ds.get_config_var("EXT_SUFFIX"),
 }))
 `
 
@@ -144,12 +147,13 @@ else:
 	}
 
 	var raw struct {
-		Version int    `json:"version"`
-		IncDir  string `json:"incdir"`
-		LibDir  string `json:"libdir"`
-		LibPy   string `json:"libpy"`
-		ShLibs  string `json:"shlibs"`
-		SysLibs string `json:"syslibs"`
+		Version   int    `json:"version"`
+		IncDir    string `json:"incdir"`
+		LibDir    string `json:"libdir"`
+		LibPy     string `json:"libpy"`
+		ShLibs    string `json:"shlibs"`
+		SysLibs   string `json:"syslibs"`
+		ExtSuffix string `json:"extsuffix"`
 	}
 	err = json.NewDecoder(buf).Decode(&raw)
 	if err != nil {
@@ -167,6 +171,7 @@ else:
 	}
 
 	cfg.Version = raw.Version
+	cfg.ExtSuffix = raw.ExtSuffix
 	cfg.CFlags = strings.Join([]string{
 		"-I" + raw.IncDir,
 	}, " ")

cmd_build.go

@@ -168,6 +168,18 @@ func runBuild(mode bind.BuildMode, cfg *BuildCfg) error {
 		}
 
 	} else {
+		buildLib := buildname + libExt
+		extext := libExt
+		if runtime.GOOS == "windows" {
+			extext = ".pyd"
+		}
+		if pycfg.ExtSuffix != "" {
+			extext = pycfg.ExtSuffix
+		}
+		modlib := "_" + cfg.Name + extext
+
+		// build the go shared library upfront to generate the header
+		// needed by our generated cpython code
 		args := []string{"build", "-buildmode=c-shared"}
 		if !cfg.Symbols {
 			// These flags will omit the various symbol tables, thereby
@@ -176,15 +188,20 @@ func runBuild(mode bind.BuildMode, cfg *BuildCfg) error {
 			// -w Omit the DWARF symbol table
 			args = append(args, "-ldflags=-s -w")
 		}
-		args = append(args, "-o", buildname+libExt, ".")
+		args = append(args, "-o", buildLib, ".")
 		fmt.Printf("go %v\n", strings.Join(args, " "))
 		cmd = exec.Command("go", args...)
 		cmdout, err = cmd.CombinedOutput()
 		if err != nil {
 			fmt.Printf("cmd had error: %v  output:\n%v\n", err, string(cmdout))
 			return err
 		}
+		// update the output name to the one with the ABI extension
+		args[len(args)-2] = modlib
+		// we don't need this initial lib because we are going to relink
+		os.Remove(buildLib)
 
+		// generate c code
 		fmt.Printf("%v build.py\n", cfg.VM)
 		cmd = exec.Command(cfg.VM, "build.py")
 		cmdout, err = cmd.CombinedOutput()
@@ -193,77 +210,59 @@ func runBuild(mode bind.BuildMode, cfg *BuildCfg) error {
 			return err
 		}
 
+		// patch c code
 		if err := patchLeaks(cfg.Name + ".c"); err != nil {
 			return err
 		}
 
-		fmt.Printf("go env CC\n")
-		cmd = exec.Command("go", "env", "CC")
-		cccmdb, err := cmd.CombinedOutput()
-		if err != nil {
-			fmt.Printf("cmd had error: %v  output:\n%v\n", err, string(cccmdb))
-			return err
-		}
-		cccmd := strings.TrimSpace(string(cccmdb))
-		// var cflags, ldflags []byte
-		// if runtime.GOOS != "windows" {
-		// 	fmt.Printf("%v-config --cflags\n", vm)
-		// 	cmd = exec.Command(vm+"-config", "--cflags") // TODO: need minor version!
-		// 	cflags, err = cmd.CombinedOutput()
-		// 	if err != nil {
-		// 		fmt.Printf("cmd had error: %v  output:\n%v\n", err, string(cflags))
-		// 		return err
-		// 	}
-		//
-		// 	fmt.Printf("%v-config --ldflags\n", vm)
-		// 	cmd = exec.Command(vm+"-config", "--ldflags")
-		// 	ldflags, err = cmd.CombinedOutput()
-		// 	if err != nil {
-		// 		fmt.Printf("cmd had error: %v  output:\n%v\n", err, string(ldflags))
-		// 		return err
-		// 	}
-		// 	fmt.Printf("build cmd: %s\nldflags: %s\n", cmd, ldflags)
-		// }
-		extext := libExt
-		if runtime.GOOS == "windows" {
-			extext = ".pyd"
+		cflags := strings.Fields(strings.TrimSpace(pycfg.CFlags))
+		cflags = append(cflags, "-fPIC", "-Ofast")
+		if include, exists := os.LookupEnv("GOPY_INCLUDE"); exists {
+			cflags = append(cflags, "-I"+filepath.ToSlash(include))
 		}
-		modlib := "_" + cfg.Name + extext
-		gccargs := []string{cfg.Name + ".c", extraGccArgs, cfg.Name + "_go" + libExt, "-o", modlib}
-		gccargs = append(gccargs, strings.Fields(pycfg.AllFlags())...)
-		gccargs = append(gccargs, "-fPIC", "--shared", "-Ofast")
+
+		ldflags := strings.Fields(strings.TrimSpace(pycfg.LdFlags))
 		if !cfg.Symbols {
-			gccargs = append(gccargs, "-s")
+			ldflags = append(ldflags, "-s")
 		}
-		include, exists := os.LookupEnv("GOPY_INCLUDE")
-		if exists {
-			gccargs = append(gccargs, "-I"+filepath.ToSlash(include))
+		if lib, exists := os.LookupEnv("GOPY_LIBDIR"); exists {
+			ldflags = append(ldflags, "-L"+filepath.ToSlash(lib))
 		}
-		lib, exists := os.LookupEnv("GOPY_LIBDIR")
-		if exists {
-			gccargs = append(gccargs, "-L"+filepath.ToSlash(lib))
-		}
-		libname, exists := os.LookupEnv("GOPY_PYLIB")
-		if exists {
-			gccargs = append(gccargs, "-l"+filepath.ToSlash(libname))
+		if libname, exists := os.LookupEnv("GOPY_PYLIB"); exists {
+			ldflags = append(ldflags, "-l"+filepath.ToSlash(libname))
 		}
 
-		gccargs = func(vs []string) []string {
-			o := make([]string, 0, len(gccargs))
-			for _, v := range vs {
+		removeEmpty := func(src []string) []string {
+			o := make([]string, 0, len(src))
+			for _, v := range src {
 				if v == "" {
 					continue
 				}
 				o = append(o, v)
 			}
 			return o
-		}(gccargs)
+		}
+
+		cflags = removeEmpty(cflags)
+		ldflags = removeEmpty(ldflags)
 
-		fmt.Printf("%s %v\n", cccmd, strings.Join(gccargs, " "))
-		cmd = exec.Command(cccmd, gccargs...)
+		cflagsEnv := fmt.Sprintf("CGO_CFLAGS=%s", strings.Join(cflags, " "))
+		ldflagsEnv := fmt.Sprintf("CGO_LDFLAGS=%s", strings.Join(ldflags, " "))
+
+		env := os.Environ()
+		env = append(env, cflagsEnv)
+		env = append(env, ldflagsEnv)
+
+		fmt.Println(cflagsEnv)
+		fmt.Println(ldflagsEnv)
+
+		// build extension with go + c
+		fmt.Printf("go %v\n", strings.Join(args, " "))
+		cmd = exec.Command("go", args...)
+		cmd.Env = env
 		cmdout, err = cmd.CombinedOutput()
 		if err != nil {
-			fmt.Printf("cmd had error: %v\noutput: %v\n", err, string(cmdout))
+			fmt.Printf("cmd had error: %v  output:\n%v\n", err, string(cmdout))
 			return err
 		}
 	}

main_unix_test.go

@@ -7,7 +7,6 @@
 package main
 
 import (
-	"fmt"
 	"log"
 	"os"
 	"os/exec"
@@ -16,8 +15,6 @@ import (
 
 func init() {
 
-	// ld needs to look into the current directory to load the _go.so library
-	os.Setenv("LD_LIBRARY_PATH", fmt.Sprintf("%s:.", os.Getenv("LD_LIBRARY_PATH")))
 	testEnvironment = os.Environ()
 
 	var (