Another question about cross-compiling

[carl_caulkett]

Thanks Warfley and TRon,

I changes my Lazarus Settings to `/usr/local/bin/fpc` for the Compiler Executable, and it does, indeed as you say, dispatch the command to the correct backend. I thought I had already tried that, but obviously not 😉

Unfortunately, I've just wasted the entire morning, before realising that the build process as started by the `/usr/local/bin/fpc` setting differs from the build process started by the `/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh` setting. The difference being that the app built completely and without errors with the second setting whereas with the first setting it gave me all sorts of issues relating to paths and god knows what else!

I was starting to wonder if I had finally lost any remaining grip on tangible reality

UPDATE: I looked more closely at the `fpc` that I had used in the failing attempts. It was dated 16/05/2021 so no wonder it failed to build properly.

So the question remains: what setting to I need to put in my "Settings" -> "Environment" -> "Files" -> "Compiler Executable (e.g. fpc)"?
As previously stated, I have to switch between "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh" to build for macOS, and "/usr/local/bin/ppcrossx64" to cross-compile for Windows.

The "fpc.sh" just mentioned consists of...

Code: Bash  [Select][+][-]

1. #!/bin/sh
2. # This script starts the fpc compiler installed by fpcup
3. # and ignores any system-wide fpc.cfg files
4. # Note: maintained by fpcup; do not edit directly, your edits will be lost.
5. /Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc -n @/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.cfg "$@"
6.  

[carl_caulkett]

Thats what the compiler stub is for. The actual compiler are the ppcXXX compilers, the fpc binary is just stub which will dispatch the calls to the correct ppc compiler. So when you in your project options select the correct target architecture the compiler stub should select the correct cross compiler.

You should not need to change the compiler path to the ppcXXX compilers from the fpc (or the fpc.sh in case of fpcup). A few years ago I've built a docker pipeline with Win32 and Win64 cross compilers using fpcup and lazbuild using build configurations, and it worked quite well. I've wrote it down here

If your compiler stub has trouble finding the correct compiler executables, it's probably because they are neither in the search path nor in the same directory. The easiest solution on *nix is usually to just create a symlink into the fpc directory

So where is this platform-agnostic version of `fpc`?

[TRon]

So where is this platform-agnostic version of `fpc`?

In your specific case: /Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc

I was starting to wonder if I had finally lost any remaining grip on tangible reality

You made a classical (newbie) error, that's all. It is complicated/overwhelming if you are unfamiliar.

I have to guess a little but it seems that the cross-compiler was installed system-wide while the Lazarus installation came with its own FPC setup.

The trick there is to 'merge' the cross-compiler with the FPC compiler used by Lazarus.

If you remember, I posted a directory/file overview of my setup. I advise to have another look at it.

In the Lazarus FPC directory /Applications/Lazarus_trunk/fpc/ should be a directory located named "units" (that is, if Lazarus  was installed that way).

The (compiled) units of the cross compiler need to be tucked in that same directory using its own cpu-os name combination so that this directory resides along the "x86_64-darwin" directory (to make sure, as a sub-directory of the units directory).

The other thing that needs to be done is to copy the ppcXXX (cross-)compiler to the binary directory of FPC (or wherever FPC (fpc.cfg) expects its tools to be stored).

If FPCUpDeluxe was also used to install Lazarus then it should be possible to update the Lazarus installation with only the cross-compiler so that FPCUpDeluxe does everything (automatically) for you. That only works when the same settings in FPCUpDeluxe are used for both the Lazarus installation and building the cross-compiler.

I would advise to remove the global installed cross-compiler completely and start anew (or cheat by using the instructions that I wrote in this post and copying the required files over to the Lazarus installation first)

I apologize upfront for the messy solution/instructions. In case you are indeed trying to do things manually and if something is not matching my instructions or something seems off then please post. I wrote this all from memory so there might be something off.

[carl_caulkett]

In your specific case: /Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc

if I choose that, rather than `/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh` the build fails with "Fatal: Can't find unit system used by ListMIDIDevices".

I'll stick to switching in both places. At least it works that way 😮

[TRon]

if I choose that, rather than `/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh` the build fails with "Fatal: Can't find unit system used by ListMIDIDevices".

For the cross-compilation, yes. Because the cross-compiler is not installed alongside the FPC compiler used by Lazarus (but rather. installed system wide). "There can be only one", "one ring to rule them all" etc..

As a fair warning of someone who has been there and done that, using a standalone and system-wide installation together is a dangerous combination. In the end it'll bite you in the proverbial buttocks 

It is not a problem to have different (standalone) installations but one should definitely avoid a system wide installation (either by doing so manually or with your systems package manager if you do so. The latter which btw does not even have a clue about FPC cross-compiler setups nor does it offer them).

I'll stick to switching in both places. At least it works that way 😮

You should definitely decide that for yourself, and use whatever makes you comfortable.

Just keep this issue in mind in case you happen to bump into another hurdle and remember that you can use the compiler option -vt and/or -vd to tell/show what is actually happening.

[carl_caulkett]

if I choose that, rather than `/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh` the build fails with "Fatal: Can't find unit system used by ListMIDIDevices".

For the cross-compilation, yes. Because the cross-compiler is not installed alongside the FPC compiler used by Lazarus (but rather. installed system wide). "There can be only one", "one ring to rule them all" etc..
that you can use the compiler option -vt and/or -vd to tell/show what is actually happening.

So, should I just copy the "system-wide" cross-compiler "/usr/local/bin/ppcrossx64" to somewhere within the "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin" folder, thus making it available to Lazarus?

[TRon]

So, should I just copy the "system-wide" cross-compiler "/usr/local/bin/ppcrossx64" to somewhere within the "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin" folder, thus making it available to Lazarus?

The short answer, yes.

The long(er) answer:
That particular file (ppcrossx64) can be place next to your Lazarus' fpc executable (or where Lazarus stores its (native) ppc compiler)

The only other thing that needs to be copied are the (compiled) units that where installed by the cross-compiler (inside a directory named units usually with a sub-directory which in your case should probably be named something like aarch-win64 or arm-win64). I do not know where that location is on a mac. Invoking the cross compiler using the fpc script and adding the option -vd to compile a simple program is able to reveal where that location is (other than analyzing the fpc.cfg file that the cross-compiler uses) .

Refer to my directory tree overview of my setup to get a better understanding of how that should end up like when copied to the Lazarus FPC directory) though keep in mind that depending on how you have configured FPCUpDeluxe when Lazarus was installed the exact locations might be different (but you can verify those beforehand with a file-manager).

As long as nothing is overwritten inside your Lazarus installation directories (only add) copying files (f.e.to a wrong location) can't hurt other than making things messy, so take notes in order to remove in case something went wrong.

EDIT:
There is one thing that can make this fail and that is when the Lazarus FPC compiler and standalone cross-compiler do not match versions. They must both be the exact same version.

[carl_caulkett]

So, should I just copy the "system-wide" cross-compiler "/usr/local/bin/ppcrossx64" to somewhere within the "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin" folder, thus making it available to Lazarus?

The short answer, yes.

The long(er) answer:
That particular file (ppcrossx64) can be place next to your Lazarus' fpc executable (or where Lazarus stores its (native) ppc compiler)

Thanks! I've copied over the alias "/usr/local/bin/ppcrossx64" to the "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin" folder. What, then, should be the entry in my "Settings" -> "Environment" -> "Files" -> "Compiler Executable (e.g. fpc)" field?

[carl_caulkett]

No worries! I remembered that I still had my old Lazarus 3.4 installation so I copied the "/usr/local/bin/fpc" entry from there, and, lo and behold, I can switch from Mac to Windows with just one operation. Yay!
Thanks for your help, everybody 🙏🏽

[carl_caulkett]

Famous last words 

There is still a difference between setting the "Compiler Executable" to "/usr/local/bin/fpc" and setting it to "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh".

In the first case, the build,is failing with camidimac.pas(11,3) Error: Cannot find MacOsAll used by caMidiMac. Make sure all ppu files of a package are in its output directory. ppu in wrong directory=/usr/local/lib/fpc/3.2.2/units/x86_64-darwin/univint/MacOSAll.ppu.."

In the second case, the app builds perfectly!

[TRon]

There is still a difference between setting the "Compiler Executable" to "/usr/local/bin/fpc" and setting it to "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh".

The first thing that came to mind is that in one of the earlier made post the code was posted and I noticed inside caMacMidiForm the uses clause to include macosall.

But, that should end up in an error when cross-compiling no matter what.

The only other thing that is able to influence that is differences in fpc.cfg between those between the configuration of the native compiler vs the cross-compiler. FPC allows for specific settings to take place only when it is cross-compiling but a stand-alone cross-compiler (its fpc.cfg) does not have to take that into account (by default).

Are you able to locate anything in the native fpc.cfg compiler settings that would be able to account for dragging in the macos all unit ?

I am out of my comfort zone there because I do not have to hardware to be able to test.

[carl_caulkett]

Thanks for the reply TRon! The unit caMacMidiForm was from a test app. The unit caMidiMac (admittedly the similar names are potentially confusing!) is a unit with the OsmosePresets project, the inclusion of which is governed by {$IFDEF DARWIN} directives.

Both of the scenarios described are with the macOS Project Options selected. The MacOsAll unit should be dragged in, in both cases!

It pains me to say it, but the Windows option is working perfectly

[carl_caulkett]

The macOS "Compiler Executable" setting that DOES work is "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh"

"fpc.sh" consists of...

Code: Bash  [Select][+][-]

1. #!/bin/sh
2. # This script starts the fpc compiler installed by fpcup
3. # and ignores any system-wide fpc.cfg files
4. # Note: maintained by fpcup; do not edit directly, your edits will be lost.
5. /Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc -n @/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.cfg "$@"
6.  

while "fpc.cfg", in the same folder, consists of

Code: Pascal  [Select][+][-]

1. #
2. # Config file generated by fpcmkcfg on 30-9-24 - 13:44:42
3. # Example fpc.cfg for Free Pascal Compiler
4. #
5.  
6. # ----------------------
7. # Defines (preprocessor)
8. # ----------------------
9.  
10. #
11. # nested #IFNDEF, #IFDEF, #ENDIF, #ELSE, #DEFINE, #UNDEF are allowed
12. #
13. # -d is the same as #DEFINE
14. # -u is the same as #UNDEF
15. #
16.  
17. #
18. # Some examples (for switches see below, and the -? helppages)
19. #
20. # Try compiling with the -dRELEASE or -dDEBUG on the commandline
21. #
22.  
23. # For a release compile with optimizes and strip debuginfo
24. #IFDEF RELEASE
25.   -O2
26.   -Xs
27.   #WRITE Compiling Release Version
28. #ENDIF
29.  
30. # For a debug version compile with debuginfo and all codegeneration checks on
31. #IFDEF DEBUG
32.   -gl
33.   -Crtoi
34.   #WRITE Compiling Debug Version
35. #ELSE
36.   # Strip debuginfo from the executable if not in debug mode
37.   -Xs
38. #ENDIF
39.  
40. # assembling
41. #ifdef darwin
42. # use pipes instead of temporary files for assembling
43. -ap
44. #endif
45.  
46. # ----------------
47. # Parsing switches
48. # ----------------
49.  
50. # Pascal language mode
51. #      -Mfpc      free pascal dialect (default)
52. #      -Mobjfpc   switch some Delphi 2 extensions on
53. #      -Mdelphi   tries to be Delphi compatible
54. #      -Mtp       tries to be TP/BP 7.0 compatible
55. #      -Mgpc      tries to be gpc compatible
56. #      -Mmacpas   tries to be compatible to the macintosh pascal dialects
57. #
58. # Turn on Object Pascal extensions by default
59. #-Mobjfpc
60.  
61. # Assembler reader mode
62. #      -Rdefault  use default assembler
63. #      -Ratt      read AT&T style assembler
64. #      -Rintel    read Intel style assembler
65. #
66. # All assembler blocks are AT&T styled by default
67. #-Ratt
68.  
69. # Semantic checking
70. #      -S2        same as -Mobjfpc
71. #      -Sc        supports operators like C (*=,+=,/= and -=)
72. #      -Sa        include assertion code.
73. #      -Sd        same as -Mdelphi
74. #      -Se<x>     error options. <x> is a combination of the following:
75. #         <n> : compiler stops after <n> errors (default is 1)
76. #         w   : compiler stops also after warnings
77. #         n   : compiler stops also after notes
78. #         h   : compiler stops also after hints
79. #      -Sg        allow LABEL and GOTO
80. #      -Sh        Use ansistrings
81. #      -Si        support C++ styled INLINE
82. #      -Sk        load fpcylix unit
83. #      -SI<x>     set interface style to <x>
84. #         -SIcom    COM compatible interface (default)
85. #         -SIcorba  CORBA compatible interface
86. #      -Sm        support macros like C (global)
87. #      -So        same as -Mtp
88. #      -Sp        same as -Mgpc
89. #      -Ss        constructor name must be init (destructor must be done)
90. #      -Sx        enable exception keywords (default in Delphi/ObjFPC modes)
91. #
92. # Allow goto, inline, C-operators, C-vars
93. -Sgic
94.  
95. # ---------------
96. # Code generation
97. # ---------------
98.  
99. # Uncomment the next line if you always want static/dynamic units by default
100. # (can be overruled with -CD, -CS at the commandline)
101. #-CS
102. #-CD
103.  
104. # Set the default heapsize to 8Mb
105. #-Ch8000000
106.  
107. # Set default codegeneration checks (iocheck, overflow, range, stack)
108. #-Ci
109. #-Co
110. #-Cr
111. #-Ct
112.  
113. # Optimizer switches
114. # -Os        generate smaller code
115. # -Oa=N      set alignment to N
116. # -O1        level 1 optimizations (quick optimizations, debuggable)
117. # -O2        level 2 optimizations (-O1 + optimizations which make debugging more difficult)
118. # -O3        level 3 optimizations (-O2 + optimizations which also may make the program slower rather than faster)
119. # -Oo<x>     switch on optimalization x. See fpc -i for possible values
120. # -OoNO<x>   switch off optimalization x. See fpc -i for possible values
121. # -Op<x>     set target cpu for optimizing, see fpc -i for possible values
122.  
123. #ifdef darwin
124. #ifdef cpui386
125. -Cppentiumm
126. -Oppentiumm
127. #endif
128. #endif
129.  
130. # -----------------------
131. # Set Filenames and Paths
132. # -----------------------
133.  
134. # Both slashes and backslashes are allowed in paths
135.  
136. # path to the messagefile, not necessary anymore but can be used to override
137. # the default language
138. #-Fr/Applications/Lazarus_trunk/fpc/msg/errore.msg
139. #-Fr/Applications/Lazarus_trunk/fpc/msg/errorn.msg
140. #-Fr/Applications/Lazarus_trunk/fpc/msg/errores.msg
141. #-Fr/Applications/Lazarus_trunk/fpc/msg/errord.msg
142. #-Fr/Applications/Lazarus_trunk/fpc/msg/errorr.msg
143.  
144. # search path for unicode binary files (FPC 2.x does not know this switch)
145. #ifndef VER2
146. -FM/Applications/Lazarus_trunk/fpc/share/unicode/
147. #endif
148.  
149. # Search for $fpctarget/$fpcsubarch-$fpcmemorymodel/ subdirectory first
150. # for i8086 CPU
151. #ifdef cpui8086
152. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/$fpcsubarch-$fpcmemorymodel
153. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/$fpcsubarch-$fpcmemorymodel/*
154. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/$fpcsubarch-$fpcmemorymodel/rtl
155. #endif
156.  
157. # searchpath for units and other system dependent things
158. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget
159. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/*
160. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/rtl
161.  
162. #IFDEF FPCAPACHE_1_3
163. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/httpd13/
164. #ELSE
165. #IFDEF FPCAPACHE_2_0
166. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/httpd20
167. #ELSE
168. -Fu/Applications/Lazarus_trunk/fpc/units/$fpctarget/httpd22
169. #ENDIF
170. #ENDIF
171.  
172. # searchpath for fppkg user-specific packages
173. -Fu/Applications/Lazarus_trunk/packages.fppkg/units/$fpctarget/*
174.  
175. # searchpath for tools
176. -FD/Applications/Lazarus_trunk/fpc/bin/$FPCTARGET
177.  
178. # path to the gcclib
179. #ifdef Darwin
180. #ifdef cpui386
181. -Fl/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/lib/darwin
182. #endif
183. #ifdef cpux86_64
184. -Fl/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/lib/darwin
185. #endif
186. -FD/Library/Developer/CommandLineTools/usr/bin
187. #ifdef cpui386
188. -Fl/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib
189. #endif
190. #ifndef cpui386
191. #ifndef cpupowerpc
192. #ifndef cpupowerpc64
193. -XR/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
194. #endif
195. #endif
196. #endif
197. #endif
198.  
199.  
200. # searchpath for libraries
201. #-Fl/Applications/Lazarus_trunk/fpc/lib
202. #-Fl/lib;/usr/lib
203. -Fl/Applications/Lazarus_trunk/fpc/lib/$FPCTARGET
204.  
205. #IFNDEF Darwin
206. #DEFINE NEEDCROSSBINUTILS
207. #ENDIF
208.  
209. # never need cross-prefix when targeting the JVM
210. # (no native compiler, always cross-compiling)
211. #ifdef cpujvm
212. #undef NEEDCROSSBINUTILS
213. #endif
214.  
215. # for android cross-prefix is set by compiler
216. #ifdef android
217. #undef NEEDCROSSBINUTILS
218. #endif
219.  
220. # never need cross-prefix when targeting the i8086
221. # (no native compiler, always cross-compiling)
222. #ifdef cpui8086
223. #undef NEEDCROSSBINUTILS
224. #endif
225.  
226. # binutils prefix for cross compiling
227. #IFDEF FPC_CROSSCOMPILING
228. #IFDEF NEEDCROSSBINUTILS
229.   -XP$FPCTARGET-
230. #ENDIF
231. #ENDIF
232.  
233.  
234. # -------------
235. # Linking
236. # -------------
237.  
238. # generate always debugging information for GDB (slows down the compiling
239. # process)
240. #      -gc        generate checks for pointers
241. #      -gd        use dbx
242. #      -gg        use gsym
243. #      -gh        use heap trace unit (for memory leak debugging)
244. #      -gl        use line info unit to show more info for backtraces
245. #      -gv        generates programs tracable with valgrind
246. #      -gw        generate dwarf debugging info
247. #
248. # Enable debuginfo and use the line info unit by default
249. #-gl
250.  
251. # always pass an option to the linker
252. #-k-s
253.  
254. # Always use smartlinking on i8086, because the system unit exceeds the 64kb
255. # code limit
256. #ifdef cpui8086
257. -CX
258. -XX
259. #endif
260.  
261.  
262. # -------------
263. # Miscellaneous
264. # -------------
265.  
266. # Write always a nice FPC logo ;)
267. -l
268.  
269. # Verbosity
270. #      e : Show errors (default)       d : Show debug info
271. #      w : Show warnings               u : Show unit info
272. #      n : Show notes                  t : Show tried/used files
273. #      h : Show hints                  s : Show time stamps
274. #      i : Show general info           q : Show message numbers
275. #      l : Show linenumbers            c : Show conditionals
276. #      a : Show everything             0 : Show nothing (except errors)
277. #      b : Write file names messages   r : Rhide/GCC compatibility mode
278. #          with full path              x : Executable info (Win32 only)
279. #      v : write fpcdebug.txt with     p : Write tree.log with parse tree
280. #          lots of debugging info
281. #
282. # Display Info, Warnings and Notes
283. -viwn
284. # If you don't want so much verbosity use
285. #-vw
286.  
287.  
288.  
289. # begin fpcup do not remove : base settings
290. # Adding binary tools paths to
291. # plain bin dir and architecture bin dir so
292. # fpc 3.1+ fpcres etc can be found.
293. -FD/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin;/Applications/Lazarus_trunk/fpc
294. # library search path
295. -Fl/usr/lib/$fpctarget;/usr/lib/$fpctarget-gnu;/lib/$fpctarget;/lib/$fpctarget-gnu
296. #IFNDEF FPC_CROSSCOMPILING
297. -Fl/usr/lib/gcc
298. #ENDIF
299.  
300. # Add some extra OSX options, if any
301. #IFDEF DARWIN
302. # Prevents crti not found linking errors
303. #IFNDEF FPC_CROSSCOMPILING
304. -WM10.9
305. #ENDIF
306. #ENDIF
307.  
308. # MacOS 10.14 Mojave and newer have libs and tools in new, yet non-standard directory
309. #IFDEF DARWIN
310. -XR/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk
311. #ENDIF
312. -Fl/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib
313. -FD/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
314. # end fpcup do not remove
315.  

I have to confess that I am finding the "fpc.cfg", shown above, rather intimidating 

If someone could offer me some pointers on this, I'd be very grateful 🙏🏽

Just to reiterate, I'm after a single "Compiler Executable" which will call either the macOS "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh" command, or the "/usr/local/bin/ppcrossx64" command for Windows.

I also tried leaving the "/usr/local/bin/ppcrossx64" command in there and choosing the macOS Project Options. The build seemed to progress a long way but eventually failed on the not being able to find MacOsAll, despite me adding the source path and then the "ppu" path in "Compiler Options" -> "Paths". Lazarus itself can clearly find MacOsAll.pas because Ctrl-Enter in the code editor opens the file!

[TRon]

Just to reiterate, I'm after a single "Compiler Executable" which will call either the macOS "/Applications/Lazarus_trunk/fpc/bin/x86_64-darwin/fpc.sh" command, or the "/usr/local/bin/ppcrossx64" command for Windows.

It should be the former, which script will point to the actual fpc (front-end) compiler.

Selecting the target processor and os in the project options then should automatically invoke the ppccrossx86 cross-compiler.

BTW: perhaps it is me but I could have sworn that you mentioned windows on arm (and therefor also assume mac on arm). Neither of which seems to be true according to what I am able to see now.

I also tried leaving the "/usr/local/bin/ppcrossx64" command in there and choosing the macOS Project Options. The build seemed to progress a long way but eventually failed on the not being able to find MacOsAll, despite me adding the source path and then the "ppu" path in "Compiler Options" -> "Paths". Lazarus itself can clearly find MacOsAll.pas because Ctrl-Enter in the code editor opens the file!

Apologies for not replying to this part sooner but your previous response threw me a bit off-guard.

There is no macos(all) unit for targets that are not macos.

Reason is simple: the macosall unit binds itself to the underlying required frameworks and these do not exist on other platforms besides macos.

While on the subject of sharing, could you share the fpc.cfg used by the cross-compiler as well ? That should include the missing parts that need to be added top the fpc.cfg that was shared in your post.

[carl_caulkett]

I've just made a discovery which, while not a breakthrough, might offer a clue as to what's going on here. If I load the test app "caMacMidi.lpr" which references my midi files in exactly the same way as my main project "OsmosePresets", the project builds in both macOS and Windows modes.

The first image shows how the test app "caMacMidi.lpr" is structured.

If I load the main app "OsmosePresets.lpr", the structure of which is shown in the second image, the build fails with the message "camidimac.pas(11,3) Error: Cannot find MacOsAll used by caMidiMac. Make sure all ppu files of a package are in its output directory. ppu in wrong directory=/usr/local/lib/fpc/3.2.2/units/x86_64-darwin/univint/MacOSAll.ppu.."

The "camidi..." files referenced by the "../camidi/..." items are attached in the zip file.
The "MacMidi" test app and the "OsmosePresets" app will be attached to the following message.

Note that the only place in the entire code where MacOsAll is mentioned is in the file "camidimac.pas".