compiler: Add "--depfile" option writing package dependencies to given file

This is meant to be used by build systems before invoking rebuilds

3 files changed, 32 insertions, 0 deletions

diff --git a/compiler/valacompiler.vala b/compiler/valacompiler.vala
index 54c3535a5..174baded7 100644
--- a/compiler/valacompiler.vala
+++ b/compiler/valacompiler.vala
@@ -95,6 +95,7 @@ class Vala.Compiler {
 	static bool disable_colored_output;
 	static Report.Colored colored_output = Report.Colored.AUTO;
 	static string dependencies;
+	static string depfile;
 
 	static string entry_point;
 
@@ -126,6 +127,7 @@ class Vala.Compiler {
 		{ "use-fast-vapi", 0, 0, OptionArg.STRING_ARRAY, ref fast_vapis, "Use --fast-vapi output during this compile", null },
 		{ "vapi-comments", 0, 0, OptionArg.NONE, ref vapi_comments, "Include comments in generated vapi", null },
 		{ "deps", 0, 0, OptionArg.STRING, ref dependencies, "Write make-style dependency information to this file", null },
+		{ "depfile", 0, 0, OptionArg.STRING, ref depfile, "Write make-style external dependency information for build systems to this file", null },
 		{ "list-sources", 0, 0, OptionArg.NONE, ref list_sources, "Output a list of all source and binding files which are used", null },
 		{ "symbols", 0, 0, OptionArg.FILENAME, ref symbols_filename, "Output symbols file", "FILE" },
 		{ "compile", 'c', 0, OptionArg.NONE, ref compile_only, "Compile but do not link", null },
@@ -525,6 +527,10 @@ class Vala.Compiler {
 			context.write_dependencies (dependencies);
 		}
 
+		if (depfile != null) {
+			context.write_external_dependencies (depfile);
+		}
+
 		if (context.report.get_errors () > 0 || (fatal_warnings && context.report.get_warnings () > 0)) {
 			return quit ();
 		}
diff --git a/doc/valac.1 b/doc/valac.1
index 4f9d1c5dd..7f46b178e 100644
--- a/doc/valac.1
+++ b/doc/valac.1
@@ -90,6 +90,9 @@ Include comments in generated vapi
 \fB\-\-deps\fR
 Write make\-style dependency information to this file
 .TP
+\fB\-\-depfile\fR
+Write make\-style external dependency information for build systems to this file
+.TP
 \fB\-\-list\-sources\fR
 Output a list of all source and binding files which are used
 .TP
diff --git a/vala/valacodecontext.vala b/vala/valacodecontext.vala
index 47c1cede4..9bce9f19d 100644
--- a/vala/valacodecontext.vala
+++ b/vala/valacodecontext.vala
@@ -715,6 +715,29 @@ public class Vala.CodeContext {
 		stream.printf ("\n\n");
 	}
 
+	public void write_external_dependencies (string filename) {
+		var stream = FileStream.open (filename, "w");
+
+		if (stream == null) {
+			Report.error (null, "unable to open `%s' for writing".printf (filename));
+			return;
+		}
+
+		bool first = true;
+		foreach (var src in source_files) {
+			if (src.file_type != SourceFileType.SOURCE && src.used) {
+				if (first) {
+					first = false;
+					stream.printf ("%s: ", filename);
+				} else {
+					stream.puts (" \\\n\t");
+				}
+				stream.printf ("%s", src.filename);
+			}
+		}
+		stream.puts ("\n\n");
+	}
+
 	private static bool ends_with_dir_separator (string s) {
 		return Path.is_dir_separator (s.get_char (s.length - 1));
 	}