From 4b683bed42937d54a3b20386997a139913bf1936 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Mon, 10 May 2021 17:10:57 +0200
Subject: [PATCH 1/4] sys/bus: move to sys/sys_bus

Matching folder and module names make live easier
---
 sys/Makefile                        | 2 +-
 sys/{bus => sys_bus}/Makefile       | 2 --
 sys/{bus => sys_bus}/sys_bus_init.c | 0
 3 files changed, 1 insertion(+), 3 deletions(-)
 rename sys/{bus => sys_bus}/Makefile (65%)
 rename sys/{bus => sys_bus}/sys_bus_init.c (100%)

diff --git a/sys/Makefile b/sys/Makefile
index fc5c0633c238..46fbc9265298 100644
--- a/sys/Makefile
+++ b/sys/Makefile
@@ -165,7 +165,7 @@ ifneq (,$(filter suit%,$(USEMODULE)))
   DIRS += suit
 endif
 ifneq (,$(filter sys_bus,$(USEMODULE)))
-  DIRS += bus
+  DIRS += sys_bus
 endif
 ifneq (,$(filter tcp,$(USEMODULE)))
   DIRS += net/transport_layer/tcp
diff --git a/sys/bus/Makefile b/sys/sys_bus/Makefile
similarity index 65%
rename from sys/bus/Makefile
rename to sys/sys_bus/Makefile
index d66bde0cec91..48422e909a47 100644
--- a/sys/bus/Makefile
+++ b/sys/sys_bus/Makefile
@@ -1,3 +1 @@
-MODULE = sys_bus
-
 include $(RIOTBASE)/Makefile.base
diff --git a/sys/bus/sys_bus_init.c b/sys/sys_bus/sys_bus_init.c
similarity index 100%
rename from sys/bus/sys_bus_init.c
rename to sys/sys_bus/sys_bus_init.c

From 1769b6ff02dff7ea30459a53c182ecf371447102 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Mon, 10 May 2021 17:25:05 +0200
Subject: [PATCH 2/4] build-system: auto-locate modules by name

This commit introduces the MODULE_DIRS variable that works just like
EXTERNAL_MODULE_DIRS, but it is intended for internal modules. The
major difference is that external modules can have the same name as
an internal module, in which case the external module is used instead
of the internal one. This allows to provide drop-in replacements of
internal modules, which can be useful during development e.g. to
quickly benchmark different implementations.
---
 Makefile.include                       | 10 +++++++--
 drivers/Makefile                       |  2 --
 makefiles/dependency_resolution.inc.mk |  4 ----
 makefiles/locate_modules.inc.mk        | 11 ++++++++++
 sys/Makefile                           | 29 --------------------------
 sys/Makefile.dep                       |  1 +
 6 files changed, 20 insertions(+), 37 deletions(-)
 create mode 100644 makefiles/locate_modules.inc.mk

diff --git a/Makefile.include b/Makefile.include
index 0e66ee4a6e49..2b27ef195f49 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -46,6 +46,8 @@ RIOTCPU                         ?= $(RIOTBASE)/cpu
 # Deprecated to set RIOTBOARD, use EXTERNAL_BOARD_DIRS
 RIOTBOARD                       ?= $(RIOTBASE)/boards
 EXTERNAL_BOARD_DIRS             ?=
+MODULE_DIRS                     := $(RIOTBASE)/drivers
+MODULE_DIRS                     += $(RIOTBASE)/sys
 RIOTMAKE                        ?= $(RIOTBASE)/makefiles
 RIOTPKG                         ?= $(RIOTBASE)/pkg
 RIOTTOOLS                       ?= $(RIOTBASE)/dist/tools
@@ -149,6 +151,7 @@ EXTERNAL_BOARD_DIRS             := $(foreach dir,\
 EXTERNAL_MODULE_DIRS            := $(foreach dir,\
                                              $(EXTERNAL_MODULE_DIRS),\
                                              $(abspath $(dir)))
+MODULE_DIRS                     := $(foreach dir,$(MODULE_DIRS),$(abspath $(dir)))
 
 # Ensure that all directories are set and don't contain spaces.
 ifneq (, $(filter-out 1, $(foreach v,$(__DIRECTORY_VARIABLES),$(words $($(v))))))
@@ -415,6 +418,9 @@ else
 
   # process dependencies
   include $(RIOTMAKE)/dependency_resolution.inc.mk
+
+  # auto-locate modules
+  include $(RIOTMAKE)/locate_modules.inc.mk
 endif
 
 # Include Board and CPU configuration
@@ -619,8 +625,8 @@ endif
 # We assume $(LINK) to be gcc-like. Use `LINKFLAGPREFIX :=` for ld-like linker options.
 LINKFLAGPREFIX ?= -Wl,
 
-# Also build external modules
-DIRS += $(EXTERNAL_MODULE_PATHS)
+# Also build automatically located modules
+DIRS += $(EXTERNAL_MODULE_PATHS) $(MODULE_PATHS)
 
 # Define dependencies required for building (headers, downloading source files,)
 BUILDDEPS += $(RIOTBUILD_CONFIG_HEADER_C)
diff --git a/drivers/Makefile b/drivers/Makefile
index 13612d5cdb3c..3d513f9ea069 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -1,5 +1,3 @@
-DIRS += $(dir $(wildcard $(addsuffix /Makefile, $(USEMODULE))))
-
 ifneq (,$(filter saul_init_devs,$(USEMODULE)))
   DIRS += saul/init_devs
 endif
diff --git a/makefiles/dependency_resolution.inc.mk b/makefiles/dependency_resolution.inc.mk
index a3a76223c223..7b15ea2ef109 100644
--- a/makefiles/dependency_resolution.inc.mk
+++ b/makefiles/dependency_resolution.inc.mk
@@ -2,10 +2,6 @@
 # until no new modules, pkgs, or features are pull in order to catch all
 # transient dependencies
 
-# Locate used modules in $(EXTERNAL_MODULE_DIRS).
-EXTERNAL_MODULE_PATHS := $(sort $(foreach dir,$(EXTERNAL_MODULE_DIRS),\
-  $(foreach mod,$(USEMODULE),$(dir $(wildcard $(dir)/$(mod)/Makefile)))))
-
 # Back up current state to detect changes
 OLD_STATE := $(USEMODULE) $(USEPKG) $(FEATURES_USED)
 
diff --git a/makefiles/locate_modules.inc.mk b/makefiles/locate_modules.inc.mk
new file mode 100644
index 000000000000..21d64af768d6
--- /dev/null
+++ b/makefiles/locate_modules.inc.mk
@@ -0,0 +1,11 @@
+# Only locate non-pseudo-modules
+MODS2LOCATE := $(filter-out $(PSEUDOMODULES) $(NO_AUTOLOCATE),\
+               $(USEMODULE)) $(filter $(NO_PSEUDOMODULES),$(USEMODULE))
+EXTERNAL_MODULE_PATHS := $(sort $(foreach dir,$(EXTERNAL_MODULE_DIRS),\
+$(foreach mod,$(MODS2LOCATE),$(dir $(wildcard $(dir)/$(mod)/Makefile)))))
+
+# Ignore modules already located as external modules
+MODS2LOCATE := $(filter-out $(basename $(EXTERNAL_MODULE_PATHS)),$(MODS2LOCATE))
+
+MODULE_PATHS := $(sort $(foreach dir,$(MODULE_DIRS),\
+                $(foreach mod,$(MODS2LOCATE),$(dir $(wildcard $(dir)/$(mod)/Makefile)))))
diff --git a/sys/Makefile b/sys/Makefile
index 46fbc9265298..68c536451260 100644
--- a/sys/Makefile
+++ b/sys/Makefile
@@ -23,9 +23,6 @@ endif
 ifneq (,$(filter cord_lc,$(USEMODULE)))
     DIRS += net/application_layer/cord/lc
 endif
-ifneq (,$(filter cpp11-compat,$(USEMODULE)))
-  DIRS += cpp11-compat
-endif
 ifneq (,$(filter credman,$(USEMODULE)))
   DIRS += net/credman
 endif
@@ -41,9 +38,6 @@ endif
 ifneq (,$(filter dummy_thread,$(USEMODULE)))
   DIRS += test_utils/dummy_thread
 endif
-ifneq (,$(filter eepreg,$(USEMODULE)))
-  DIRS += eepreg
-endif
 ifneq (,$(filter emcute,$(USEMODULE)))
   DIRS += net/application_layer/emcute
 endif
@@ -89,9 +83,6 @@ endif
 ifneq (,$(filter l2util,$(USEMODULE)))
   DIRS += net/link_layer/l2util
 endif
-ifneq (,$(filter log_%,$(USEMODULE)))
-  DIRS += log
-endif
 ifneq (,$(filter nanocoap,$(USEMODULE)))
   DIRS += net/application_layer/nanocoap
 endif
@@ -110,12 +101,6 @@ endif
 ifneq (,$(filter netstats_neighbor,$(USEMODULE)))
   DIRS += net/netstats
 endif
-ifneq (,$(filter sema,$(USEMODULE)))
-  DIRS += sema
-endif
-ifneq (,$(filter sema_inv,$(USEMODULE)))
-  DIRS += sema_inv
-endif
 ifneq (,$(filter sixlowpan,$(USEMODULE)))
   DIRS += net/network_layer/sixlowpan
 endif
@@ -131,9 +116,6 @@ endif
 ifneq (,$(filter sock_util,$(USEMODULE)))
   DIRS += net/sock
 endif
-ifneq (,$(filter oneway_malloc,$(USEMODULE)))
-  DIRS += oneway-malloc
-endif
 ifneq (,$(filter posix_inet,$(USEMODULE)))
   DIRS += posix/inet
 endif
@@ -161,12 +143,6 @@ endif
 ifneq (,$(filter shell_commands,$(USEMODULE)))
   DIRS += shell/commands
 endif
-ifneq (,$(filter suit%,$(USEMODULE)))
-  DIRS += suit
-endif
-ifneq (,$(filter sys_bus,$(USEMODULE)))
-  DIRS += sys_bus
-endif
 ifneq (,$(filter tcp,$(USEMODULE)))
   DIRS += net/transport_layer/tcp
 endif
@@ -188,10 +164,5 @@ endif
 ifneq (,$(filter ztimer_core,$(USEMODULE)))
     DIRS += ztimer
 endif
-ifneq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
-  FILTER += xtimer
-endif
-
-DIRS += $(dir $(wildcard $(addsuffix /Makefile, $(filter-out $(FILTER), $(USEMODULE)))))
 
 include $(RIOTBASE)/Makefile.base
diff --git a/sys/Makefile.dep b/sys/Makefile.dep
index 73b0fa818b61..92d85de4cfef 100644
--- a/sys/Makefile.dep
+++ b/sys/Makefile.dep
@@ -698,6 +698,7 @@ ifneq (,$(filter xtimer,$(USEMODULE)))
     endif
   else
   # ztimer_xtimer_compat is used, all of *xtimer's API will be mapped on ztimer.*
+  NO_AUTOLOCATE += xtimer
   endif
 endif
 

From 74bd5afa4fc5d2e60bfb0131f322553d1d3a64eb Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Tue, 11 May 2021 10:58:42 +0200
Subject: [PATCH 3/4] fixup! build-system: auto-locate modules by name

---
 Makefile.include | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Makefile.include b/Makefile.include
index 2b27ef195f49..250328479dd5 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -418,11 +418,11 @@ else
 
   # process dependencies
   include $(RIOTMAKE)/dependency_resolution.inc.mk
-
-  # auto-locate modules
-  include $(RIOTMAKE)/locate_modules.inc.mk
 endif
 
+# auto-locate modules
+include $(RIOTMAKE)/locate_modules.inc.mk
+
 # Include Board and CPU configuration
 INCLUDES += $(addprefix -I,$(wildcard $(BOARDDIR)/include))
 include $(BOARDDIR)/Makefile.include

From 3d2fca212160e47fb8d84a33297b6ba9f624e6d8 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Tue, 11 May 2021 12:20:31 +0200
Subject: [PATCH 4/4] fixup! build-system: auto-locate modules by name

---
 Makefile.include                       | 5 ++---
 makefiles/dependency_resolution.inc.mk | 3 +++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Makefile.include b/Makefile.include
index 250328479dd5..f5515c2ceaff 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -406,6 +406,8 @@ ifeq (1,$(TEST_KCONFIG))
   USEMODULE := $(KCONFIG_MODULES)
   KCONFIG_PACKAGES := $(call lowercase,$(patsubst CONFIG_PACKAGE_%,%,$(filter CONFIG_PACKAGE_%,$(.VARIABLES))))
   USEPKG := $(KCONFIG_PACKAGES)
+  # auto-locate modules
+  include $(RIOTMAKE)/locate_modules.inc.mk
 else
   # check if required features are provided and update $(FEATURES_USED)
   include $(RIOTMAKE)/features_check.inc.mk
@@ -420,9 +422,6 @@ else
   include $(RIOTMAKE)/dependency_resolution.inc.mk
 endif
 
-# auto-locate modules
-include $(RIOTMAKE)/locate_modules.inc.mk
-
 # Include Board and CPU configuration
 INCLUDES += $(addprefix -I,$(wildcard $(BOARDDIR)/include))
 include $(BOARDDIR)/Makefile.include
diff --git a/makefiles/dependency_resolution.inc.mk b/makefiles/dependency_resolution.inc.mk
index 7b15ea2ef109..b740a3f3745f 100644
--- a/makefiles/dependency_resolution.inc.mk
+++ b/makefiles/dependency_resolution.inc.mk
@@ -2,6 +2,9 @@
 # until no new modules, pkgs, or features are pull in order to catch all
 # transient dependencies
 
+# auto-locate modules
+include $(RIOTMAKE)/locate_modules.inc.mk
+
 # Back up current state to detect changes
 OLD_STATE := $(USEMODULE) $(USEPKG) $(FEATURES_USED)