Request solidity metadata only for compiler versions 0.4.7 and higher

common/compiler/solidity.go

@@ -25,21 +25,21 @@ import (
 	"io/ioutil"
 	"os/exec"
 	"regexp"
+	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
 var (
-	versionRegexp = regexp.MustCompile(`[0-9]+\.[0-9]+\.[0-9]+`)
+	versionRegexp = regexp.MustCompile(`([0-9]+)\.([0-9]+)\.([0-9]+)`)
-	solcParams    = []string{
+	spmu          = &sync.Mutex{} // protects access to mutating _solcParams variable (contents are never mutated)
-		"--combined-json", "bin,abi,userdoc,devdoc,metadata",
+	_solcParams    = []string{}   // zero-len means uninitialized, protected by spmu
-		"--add-std",  // include standard lib contracts
-		"--optimize", // code optimizer switched on
-	}
 )
 
+
 type Contract struct {
 	Code string       `json:"code"`
 	Info ContractInfo `json:"info"`
@@ -68,6 +68,58 @@ type solcOutput struct {
 	Version   string
 }
 
+func findSolcParams(solc string) []string {
+	spmu.Lock()
+	defer spmu.Unlock()
+
+	if ( len(_solcParams) != 0 ) {
+		return _solcParams
+	} else {
+		recent, _ := atLeast047(solc) // on err, we default to considering the solidity version recent, see atLeast047
+		var mbmeta string
+		if ( recent ) {
+			mbmeta = ",metadata"
+		} else {
+			mbmeta = ""
+		}
+		_solcParams = []string{
+			"--combined-json", "bin,abi,userdoc,devdoc" + mbmeta,
+			"--add-std",  // include standard lib contracts
+			"--optimize", // code optimizer switched on
+		}
+		return _solcParams
+	}
+}
+
+func atLeast047(solc string) (bool, error) {
+	var (
+		solidity *Solidity
+		major    int
+		minor    int
+		patch    int
+		err      error
+	)
+	solidity, err = SolidityVersion(solc)
+	if ( err != nil ) {
+		return true, err
+	}
+
+	matches := versionRegexp.FindStringSubmatch( solidity.Version )
+	major, err = strconv.Atoi( matches[1] )
+	if ( err != nil ) {
+		return true, err
+	}
+	minor, err = strconv.Atoi( matches[2] )
+	if ( err != nil ) {
+		return true, err
+	}
+	patch, err = strconv.Atoi( matches[3] )
+	if ( err != nil ) {
+		return true, err
+	}
+	return (major > 0 || minor > 4 || patch > 6), nil
+}
+
 // SolidityVersion runs solc and parses its version output.
 func SolidityVersion(solc string) (*Solidity, error) {
 	if solc == "" {
@@ -95,10 +147,11 @@ func CompileSolidityString(solc, source string) (map[string]*Contract, error) {
 	if solc == "" {
 		solc = "solc"
 	}
+	solcParams := findSolcParams(solc)
 	args := append(solcParams, "--")
 	cmd := exec.Command(solc, append(args, "-")...)
 	cmd.Stdin = strings.NewReader(source)
-	return runsolc(cmd, source)
+	return runsolc(cmd, solcParams, source)
 }
 
 // CompileSolidity compiles all given Solidity source files.
@@ -113,12 +166,13 @@ func CompileSolidity(solc string, sourcefiles ...string) (map[string]*Contract,
 	if solc == "" {
 		solc = "solc"
 	}
+	solcParams := findSolcParams(solc)
 	args := append(solcParams, "--")
 	cmd := exec.Command(solc, append(args, sourcefiles...)...)
-	return runsolc(cmd, source)
+	return runsolc(cmd, solcParams, source)
 }
 
-func runsolc(cmd *exec.Cmd, source string) (map[string]*Contract, error) {
+func runsolc(cmd *exec.Cmd, solcParams []string, source string) (map[string]*Contract, error) {
 	var stderr, stdout bytes.Buffer
 	cmd.Stderr = &stderr
 	cmd.Stdout = &stdout