Draft: Support generating a compile_commands.json file

This is still very rough and unfinished.

Author: matthijskooijman

arduino/builder/compilation_database.go

@@ -0,0 +1,73 @@
+package builder
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/arduino/go-paths-helper"
+	"io/ioutil"
+	"os"
+	"os/exec"
+)
+
+type compilationCommand struct {
+	Directory string   `json:"directory"`
+	Arguments []string `json:"arguments"`
+	File      string   `json:"file"`
+}
+
+type CompilationDatabase struct {
+	contents []compilationCommand
+	filename *paths.Path
+}
+
+func NewCompilationDatabase(filename *paths.Path) *CompilationDatabase {
+	return &CompilationDatabase{
+		filename: filename,
+	}
+}
+
+func (db *CompilationDatabase) UpdateFile(complete bool) {
+	// TODO: Read any existing file and use its contents for any
+	// kept files, or any files not in db.contents if !complete.
+	fmt.Printf("Writing compilation database to \"%s\"...\n", db.filename.String())
+
+	contents := db.contents
+	jsonContents, err := json.MarshalIndent(contents, "", " ")
+	if err != nil {
+		fmt.Printf("Error serializing compilation database: %s", err)
+		return
+	}
+	err = ioutil.WriteFile(db.filename.String(), jsonContents, 0644)
+	if err != nil {
+		fmt.Printf("Error writing compilation database: %s", err)
+	}
+}
+
+func (db *CompilationDatabase) dirForCommand(command *exec.Cmd) string {
+	// This mimics what Cmd.Run also does: Use Dir if specified,
+	// current directory otherwise
+	if command.Dir != "" {
+		return command.Dir
+	} else {
+		dir, err := os.Getwd()
+		if err != nil {
+			fmt.Printf("Error getting current directory for compilation database: %s", err)
+			return ""
+		}
+		return dir
+	}
+}
+
+func (db *CompilationDatabase) ReplaceEntry(filename *paths.Path, command *exec.Cmd) {
+	entry := compilationCommand{
+		Directory: db.dirForCommand(command),
+		Arguments: command.Args,
+		File:      filename.String(),
+	}
+
+	db.contents = append(db.contents, entry)
+}
+
+func (db *CompilationDatabase) KeepEntry(filename *paths.Path) {
+	// TODO
+}

commands/compile/compile.go

@@ -116,6 +116,9 @@ func Compile(ctx context.Context, req *rpc.CompileReq, outStream, errStream io.W
 	builderCtx.PackageManager = pm
 	builderCtx.FQBN = fqbn
 	builderCtx.SketchLocation = sketch.FullPath
+	builderCtx.CompilationDatabase = bldr.NewCompilationDatabase(
+		sketch.FullPath.Join("compile_commands.json"),
+	)
 
 	// FIXME: This will be redundant when arduino-builder will be part of the cli
 	builderCtx.HardwareDirs = configuration.HardwareDirectories(configuration.Settings)

legacy/builder/builder.go

@@ -96,6 +96,11 @@ func (s *Builder) Run(ctx *types.Context) error {
 
 	mainErr := runCommands(ctx, commands)
 
+	// TODO: Make proper step?
+	if ctx.CompilationDatabase != nil {
+		ctx.CompilationDatabase.UpdateFile(mainErr != nil)
+	}
+
 	commands = []types.Command{
 		&PrintUsedAndNotUsedLibraries{SketchError: mainErr != nil},
 

legacy/builder/builder_utils/utils.go

@@ -258,6 +258,9 @@ func compileFileWithRecipe(ctx *types.Context, sourcePath *paths.Path, source *p
 			return nil, errors.WithStack(err)
 		}
 	} else if ctx.Verbose {
+		if ctx.CompilationDatabase != nil {
+			ctx.CompilationDatabase.KeepEntry(source)
+		}
 		logger.Println(constants.LOG_LEVEL_INFO, constants.MSG_USING_PREVIOUS_COMPILED_FILE, objectFile)
 	}
 

legacy/builder/types/context.go

@@ -19,6 +19,7 @@ import (
 	"io"
 	"strings"
 
+	"github.com/arduino/arduino-cli/arduino/builder"
 	"github.com/arduino/arduino-cli/arduino/cores"
 	"github.com/arduino/arduino-cli/arduino/cores/packagemanager"
 	"github.com/arduino/arduino-cli/arduino/libraries"
@@ -163,6 +164,9 @@ type Context struct {
 
 	// Sizer results
 	ExecutableSectionsSize ExecutablesFileSections
+
+	// Compilation Database to build/update
+	CompilationDatabase *builder.CompilationDatabase
 }
 
 // ExecutableSectionSize represents a section of the executable output file