Add showdeps script.

2 files changed, 42 insertions, 7 deletions

diff --git a/Makefile b/Makefile
index 8a50d02..505b8f1 100644
--- a/Makefile
+++ b/Makefile
@@ -7,8 +7,8 @@ CFLAGS += -Wall -Wpedantic -O -cc-options,-std=c++17 -ld-options,-mwindows
 CFLAGS += -DUNICODE -D_UNICODE
 LDFLAGS += -lcomctl32 -luxtheme
 
-all: b/$(EXE)
-	cp $< "C:\Users\John\Desktop\Delat"
+all: showdeps b/$(EXE)
+	cp b/$(EXE) "C:\Users\John\Desktop\Delat"
 
 clean:
 	rm -fr b/$(EXE) b/*.obj
@@ -16,10 +16,7 @@ clean:
 TAGS: c/*.cpp c/*.h pl/*.pl
 	etags c/*.cpp c/*.h -lprolog pl/*.pl
 
-deps.mk: c/*.cpp
-	perl makedeps
-
-b/$(EXE): Makefile deps.mk c/main.cpp $(OBJ) $(PL)
+b/$(EXE): Makefile c/main.cpp $(OBJ) $(PL)
 	$(CC) -v $(CFLAGS) $(LDFLAGS) -goal true -o $@ c/main.cpp $(OBJ) $(PL)
 
 b/resource.obj: c/resource.h c/resource.rc c/application.manifest
@@ -28,6 +25,16 @@ b/resource.obj: c/resource.h c/resource.rc c/application.manifest
 b/%.obj: c/%.cpp
 	$(CC) -c $(CFLAGS) -o $@ $<
 
+# showdeps prints a short summary of which dependencies have changed,
+# causing which targets to be rebuilt. It is run by the `all' target
+# by default.
+.PHONY: showdeps
+showdeps:
+	@perl showdeps
+
 # deps.mk includes additional, dynamically generated dependencies for
-# b/*.obj and b/EpisodeBrowser.exe.
+# b/*.obj and b/EpisodeBrowser.exe. Because it is included below, GNU
+# make should build deps.mk automatically.
+deps.mk: c/*.cpp
+	perl makedeps
 -include deps.mk
diff --git a/showdeps b/showdeps
new file mode 100644
index 0000000..f59aeca
--- /dev/null
+++ b/showdeps
@@ -0,0 +1,28 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+my @targets;
+my @keys;
+my %prereqs;
+
+$ENV{LANGUAGE} = "en_US";
+for (`make --debug=b -n`) {
+	next if not /Prerequisite `([^']+)' is newer than target `([^']+)'/;
+
+	# Don't consider prerequisites that are targets.
+	unless ($ARGV[0] and $ARGV[0] eq '-a') {
+		push @targets, $2 if not grep { $_ eq $2 } @targets;
+		next if grep { $_ eq $1 } @targets;
+	}
+
+	push @keys, $1 if not grep { $_ eq $1 } @keys;
+	push @{$prereqs{$1}}, $2 if not grep { $_ eq $2 } @{$prereqs{$1}};
+}
+
+if (@keys) {
+	print "---\n";
+	print "$_ -> @{$prereqs{$_}}\n" for @keys;
+	print "---\n";
+}