[apidiff] Fix the comparison with the previous commit (#5690)

The removal of the XML files broke the comparison with the previous
commit. It did NOT fail the original PR because the targets were
in the previous commit.

And it will fail this PR because the previous commit still does not
have the targets - but it _should_ be fine, once merged, for all
future PR.

Fixes https://github.com/xamarin/maccore/issues/1452

tools/apidiff/Makefile

@@ -185,10 +185,25 @@ $(APIDIFF_DIR)/references/xi/%.xml: temp/%.dll $(MONO_API_INFO)
 	$(Q) mkdir -p $(dir $@) $(dir $(APIDIFF_DIR)/references/xi/$*)
 	$(QF_GEN) mono --debug $(MONO_API_INFO) $< -o $(APIDIFF_DIR)/references/xi/$*.xml
 
+$(APIDIFF_DIR)/updated-references/xi/%.xml: $(IOS_DESTDIR)$(MONOTOUCH_PREFIX)/lib/mono/%.dll $(MONO_API_INFO)
+	$(Q) mkdir -p $(dir $@) $(dir $(APIDIFF_DIR)/references/xm/$*)
+	$(QF_GEN) mono --debug $(MONO_API_INFO) $< -o $(APIDIFF_DIR)/references/xm/$*.xml
+
 $(APIDIFF_DIR)/references/xm/%.xml: temp/%.dll $(MONO_API_INFO)
 	$(Q) mkdir -p $(dir $@) $(dir $(APIDIFF_DIR)/references/xm/$*)
 	$(QF_GEN) mono --debug $(MONO_API_INFO) $< -o $(APIDIFF_DIR)/references/xm/$*.xml
 
+$(APIDIFF_DIR)/updated-references/xm/%.xml: $(MAC_DESTDIR)$(MAC_FRAMEWORK_CURRENT_DIR)/lib/mono/%.dll $(MONO_API_INFO)
+	$(Q) mkdir -p $(dir $@) $(dir $(APIDIFF_DIR)/references/xm/$*)
+	$(QF_GEN) mono --debug $(MONO_API_INFO) $< -o $(APIDIFF_DIR)/references/xm/$*.xml
+
+update-tvos-refs: $(TVOS_REFS)
+update-watchos-refs: $(WATCHOS_REFS)
+update-ios-refs: $(IOS_REFS)
+update-mac-refs: $(MAC_REFS)
+
+update-refs: $(WATCHOS_REFS) $(TVOS_REFS) $(IOS_REFS) $(MAC_REFS)
+
 # targets to verify that the 32-bit and 64-bit assemblies have identical API.
 
 verify-reference-assemblies-ios: $(APIDIFF_DIR)/temp/native-32/Xamarin.iOS.xml $(APIDIFF_DIR)/temp/native-64/Xamarin.iOS.xml

tools/apidiff/README.md

@@ -1,26 +1,14 @@
 # New Releases
 
-Note: Don't forget to :warning: **build** :warning: the XI/XM assemblies before trying to regenerate the XML files.
-
-Doing a `make update-refs` will update the XML files where we keep the current **public** API.
-
-The result should be added/committed to git so every future revisions can be compared to the reference files.
-
-= Update reference sources using the dlls from the System version of XI/XM =
-
-    make update-ios-refs     -j IOS_DESTDIR= IOS_INSTALL_VERSION=Current
-    make update-watchos-refs -j IOS_DESTDIR= IOS_INSTALL_VERSION=Current
-    make update-tvos-refs    -j IOS_DESTDIR= IOS_INSTALL_VERSION=Current
-    make update-mac-refs     -j MAC_DESTDIR= MAC_INSTALL_VERSION=Current
-
-You can change *_INSTALL_VERSION to other than Current if you have a different version
-installed (say you have XI 9.4.0.0 installed in /Library/Frameworks/Xamarin.iOS.framework/Versions/9.4.0.0,
-in which case you can do IOS_INSTALL_VERSION=9.4.0.0
+Inside `Make.config` update the `APIDIFF_REFERENCES=` line to point to the `bundle.zip` URL of the currently stable version. E.g.
 
+```
+APIDIFF_REFERENCES=https://bosstoragemirror.blob.core.windows.net/wrench/jenkins/d15-9/2dc06c712629feeb179ed112a590d9922caac6e7/53/package/bundle.zip
+```
 
 # New Revisions
 
-On the bots each revision rebuilds every assemblies. Each of them will be compared to the XML reference files. Any changes (addition/removal) to the public API will be reported in HTML files.
+On the bots each revision rebuilds every assemblies. Each of them will be compared to the downloaded stable version from `APIDIFF_REFERENCES`. Any changes (addition/removal) to the public API will be reported in HTML files.
 
 This can be done manually with `make`. The `.\diff\` directory will contain the diffs in HTML format.