Allow dep-file generation in GCC preprocessor

Author: cmaglie

internal/arduino/builder/internal/detector/detector.go

@@ -360,7 +360,7 @@ func (l *SketchLibrariesDetector) gccPreprocessTask(sourceFile *sourceFile, buil
 		includeFolders = append(includeFolders, extraInclude)
 	}
 
-	return preprocessor.GCC(sourceFile.SourcePath, paths.NullPath(), includeFolders, buildProperties)
+	return preprocessor.GCC(sourceFile.SourcePath, paths.NullPath(), includeFolders, buildProperties, nil)
 }
 
 func (l *SketchLibrariesDetector) findMissingIncludesInCompilationUnit(

internal/arduino/builder/internal/preprocessor/arduino_preprocessor.go

@@ -45,7 +45,7 @@ func PreprocessSketchWithArduinoPreprocessor(
 
 	sourceFile := buildPath.Join("sketch", sk.MainFile.Base()+".cpp")
 	targetFile := buildPath.Join("preproc", "sketch_merged.cpp")
-	gccResult := GCC(sourceFile, targetFile, includeFolders, buildProperties).Run(ctx)
+	gccResult := GCC(sourceFile, targetFile, includeFolders, buildProperties, nil).Run(ctx)
 	verboseOut.Write(gccResult.Stdout)
 	verboseOut.Write(gccResult.Stderr)
 	if gccResult.Error != nil {

internal/arduino/builder/internal/preprocessor/ctags.go

@@ -67,7 +67,7 @@ func PreprocessSketchWithCtags(
 	}
 
 	// Run GCC preprocessor
-	result := GCC(unpreprocessedSourceFile, ctagsTarget, includes, buildProperties).Run(ctx)
+	result := GCC(unpreprocessedSourceFile, ctagsTarget, includes, buildProperties, nil).Run(ctx)
 	stdout.Write(result.Stdout)
 	stderr.Write(result.Stderr)
 	if err := result.Error; err != nil {

internal/arduino/builder/internal/preprocessor/gcc.go

@@ -30,6 +30,7 @@ import (
 func GCC(
 	sourceFilePath, targetFilePath *paths.Path,
 	includes paths.PathList, buildProperties *properties.Map,
+	depFile *paths.Path,
 ) *runner.Task {
 	gccBuildProperties := properties.NewMap()
 	gccBuildProperties.Set("preproc.macros.flags", "-w -x c++ -E -CC")
@@ -62,6 +63,11 @@ func GCC(
 	// to create a /dev/null.d dependency file, which won't work.
 	args = f.Filter(args, f.NotEquals("-MMD"))
 
+	// If a depFile has been specified add the necessary arguments to generate it
+	if depFile != nil {
+		args = append(args, "-MMD", "-MF", depFile.String())
+	}
+
 	// Limit the stderr output to 100 KiB
 	// https://github.com/arduino/arduino-cli/pull/2883
 	return runner.NewTaskWithLimitedStderr(100*1024, args...)