[geary/wip/engine-header-missing-build-failure] Fix occasional "geary-engine.h: No such file or directory" build errors

[Michael Gratton <mjog src gnome org>]

commit 1dd36d846a1c78d4527a7d58793bfba419a825b2
Author: Michael Gratton <mike vee net>
Date:   Thu Nov 29 09:56:25 2018 +1100

    Fix occasional "geary-engine.h: No such file or directory" build errors
    
    E.g. https://gitlab.gnome.org/GNOME/geary/-/jobs/156541
    
    On a sufficiently (non?) parallel system, targets that depend on
    geary-engine.h may get built before the geary_engine_internal_vapi
    custom target that fixes its location is executed. This removes the
    workaround for b.g.o #731322 since that was fixed in 0.40, and updates
    workaround for the internal VAPI to be minimally intrusive.

 src/engine/meson.build | 61 ++++++++++++++++++++++----------------------------
 1 file changed, 27 insertions(+), 34 deletions(-)
---
diff --git a/src/engine/meson.build b/src/engine/meson.build
index 222a0edc..a0762bcd 100644
--- a/src/engine/meson.build
+++ b/src/engine/meson.build
@@ -337,69 +337,62 @@ geary_engine_dependencies = [
   sqlite
 ]
 
+build_dir = meson.current_build_dir()
+
+# Generate internal VAPI for unit testing. See Meson issue
+# https://github.com/mesonbuild/meson/issues/1781 for official
+# internal VAPI support.
 geary_engine_vala_options = geary_vala_options
 geary_engine_vala_options += [
-  # Nasty hack to make sure engine internal VAPI is generated. See
-  # Meson issue https://github.com/mesonbuild/meson/issues/1781 for
-  # official internal VAPI support. See Vala Bug 731322 about the
-  # specifics of the arguments used below to generate the internal
-  # VAPI. In particular, the header filenames must not contain any
-  # paths or else the internal vapi will use the public header, not
-  # the internal header. Of course these paths breaks the build, so we
-  # fix it up using cp below. The internal VAPI is correctly put in
-  # Meson's base working directory,
-  '--header=geary-engine.h',
-  '--internal-vapi=../geary-engine-internal.vapi',
-  '--internal-header=geary-engine-internal.h'
+  '--internal-header=@0@/geary-engine-internal.h'.format(build_dir),
+  '--internal-vapi=@0@/geary-engine-internal.vapi'.format(build_dir)
 ]
 
 geary_engine_lib = static_library('geary-engine',
   geary_engine_sources,
   dependencies: geary_engine_dependencies,
-  link_with: sqlite3_unicodesn_lib,
   include_directories: config_h_dir,
   vala_args: geary_engine_vala_options,
   c_args: geary_c_options,
 )
 
-geary_engine_dep = declare_dependency(
-  link_with: [
-    geary_engine_lib,
-    sqlite3_unicodesn_lib,
-  ],
-  include_directories: include_directories('.'),
-)
-
-# Dummy target to fix the location of the public and internal headers,
-# and tell Meson about the internal VAPI
-geary_engine_internal_vapi = custom_target(
-  'geary-engine-internal-vapi',
-  input: geary_engine_sources,
+# Dummy target to tell Meson about the internal VAPI given the
+# workaround above, and fix the VAPI header to work around
+# GNOME/vala#358
+geary_engine_internal_header_fixup = custom_target(
+  'geary_engine_internal_header_fixup',
+  source: geary_engine_sources,
   output: [
     'geary-engine-internal.h',
     'geary-engine-internal.vapi',
   ],
   command: [
-    find_program('cp'),
-    'geary-engine.h',
-    'geary-engine-internal.h',
-    '@OUTDIR@',
+    find_program('sed'),
+    '-i',
+    's/geary-engine.h/geary-engine-internal.h/g',
+    '@OUTDIR@/geary-engine-internal.vapi',
   ],
   depends: geary_engine_lib
 )
 
+geary_engine_dep = declare_dependency(
+  link_with: [
+    geary_engine_lib,
+    sqlite3_unicodesn_lib
+  ],
+  include_directories: include_directories('.')
+)
+
 geary_engine_internal_dep = declare_dependency(
   # Can't just include geary_engine_lib in link_with since that will
   # pull in the public header and we get duplicate symbol errors.
   link_args: [
-    '-L' + meson.build_root() + '/src/engine',
+    '-L' + build_dir,
     '-lgeary-engine'
   ],
   link_with: [
     sqlite3_unicodesn_lib,
   ],
   include_directories: include_directories('.'),
-  sources: [
-    geary_engine_internal_vapi
-  ],
+  sources: geary_engine_internal_header_fixup
 )