reimplement build-dep via apts normal resolver

build-dep was implemented by parsing the build-dependencies of a package
and figuring out which packages to install/remove based on this. That
means that for the first level of dependencies build-dep was
implementing its very own resolver with all the benefits (aka: bugs)
this gives us for not using the existing resolver for all levels.

Making this work involves generating a dummy binary package with fitting
Depends and Conflicts and as we can't create them out of thin air the
cache generation needs to be involved so we end up writing a Packages
file which we want to parse – after we have parsed the other Packages
files already. With .dsc/.deb files we could add them before we started
parsing anything.

With a bit of care we can avoid generating too much data we have to
throw away again (as many parts assume that e.g. the count of packages
doesn't change midair), so that on a speed front there shouldn't be
much of a difference, but output can be slightly confusing as if we have
a completely valid cache on disk the "Reading package lists... Done" is
printed two times – but apt is pretty quick about it in that case.

Closes: #137560, #444930, #489911, #583914, #728317, #812173

1 files changed, 59 insertions, 9 deletions

diff --git a/test/integration/test-bug-632221-cross-dependency-satisfaction b/test/integration/test-bug-632221-cross-dependency-satisfaction
index dad6e47fa..066e29d99 100755
--- a/test/integration/test-bug-632221-cross-dependency-satisfaction
+++ b/test/integration/test-bug-632221-cross-dependency-satisfaction
@@ -35,17 +35,45 @@ insertsource 'unstable' 'source-specific-armel' 'armel' '1' 'Build-Depends: spec
 
 setupaptarchive
 
-testfailureequal "Reading package lists...
+testfailureequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
-E: Build-Depends dependency for forbidden-no can't be satisfied because amdboot:any is not allowed on 'Multi-Arch: no' packages" aptget build-dep forbidden-no -s -a armel
-testfailureequal "Reading package lists...
+Some packages could not be installed. This may mean that you have
+requested an impossible situation or if you are using the unstable
+distribution that some required packages have not yet been created
+or been moved out of Incoming.
+The following information may help to resolve the situation:
+
+The following packages have unmet dependencies:
+ builddeps:forbidden-no:armel : Depends: amdboot:any but it is not installable
+E: Unable to correct problems, you have held broken packages.' aptget build-dep forbidden-no -s -a armel
+testfailureequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
-E: Build-Depends dependency for forbidden-same can't be satisfied because libc6:any is not allowed on 'Multi-Arch: same' packages" aptget build-dep forbidden-same -s -a armel
-testfailureequal "Reading package lists...
+Some packages could not be installed. This may mean that you have
+requested an impossible situation or if you are using the unstable
+distribution that some required packages have not yet been created
+or been moved out of Incoming.
+The following information may help to resolve the situation:
+
+The following packages have unmet dependencies:
+ builddeps:forbidden-same:armel : Depends: libc6:any but it is not installable
+E: Unable to correct problems, you have held broken packages.' aptget build-dep forbidden-same -s -a armel
+testfailureequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
-E: Build-Depends dependency for forbidden-foreign can't be satisfied because doxygen:any is not allowed on 'Multi-Arch: foreign' packages" aptget build-dep forbidden-foreign -s -a armel
+Some packages could not be installed. This may mean that you have
+requested an impossible situation or if you are using the unstable
+distribution that some required packages have not yet been created
+or been moved out of Incoming.
+The following information may help to resolve the situation:
+
+The following packages have unmet dependencies:
+ builddeps:forbidden-foreign:armel : Depends: doxygen:any but it is not installable
+E: Unable to correct problems, you have held broken packages.' aptget build-dep forbidden-foreign -s -a armel
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   libc6 specific
@@ -55,6 +83,7 @@ Inst specific (1.0 unstable [amd64])
 Conf libc6 (1.0 unstable [amd64])
 Conf specific (1.0 unstable [amd64])' aptget build-dep source-specific-amd64 -s
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   libc6 specific
@@ -65,6 +94,7 @@ Conf libc6 (1.0 unstable [amd64])
 Conf specific (1.0 unstable [amd64])' aptget build-dep source-specific-amd64 -s -a armel
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   libc6:armel specific:armel
@@ -74,6 +104,7 @@ Inst specific:armel (1.0 unstable [armel])
 Conf libc6:armel (1.0 unstable [armel])
 Conf specific:armel (1.0 unstable [armel])' aptget build-dep source-specific-armel -s
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   libc6:armel specific:armel
@@ -84,6 +115,7 @@ Conf libc6:armel (1.0 unstable [armel])
 Conf specific:armel (1.0 unstable [armel])' aptget build-dep source-specific-armel -s -a armel
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot cool doxygen foreigner libc6 libc6-dev libfwibble-dev libfwibble1
@@ -109,6 +141,7 @@ Conf libfwibble-dev (1.0 unstable [amd64])
 Conf linux-stuff (1.0 unstable [amd64])' aptget build-dep apt -s
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot arm-stuff:armel cool doxygen foreigner libc6 libc6:armel libc6-dev
@@ -165,6 +198,7 @@ Conf libfwibble1 (1.0 unstable [armel])
 Conf libfwibble-dev (1.0 unstable [armel])' aptget build-dep apt -s
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot:amd64 cool doxygen foreigner libc6 libc6:amd64 libc6-dev
@@ -202,9 +236,12 @@ testsuccessequal 'Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot doxygen libc6 libc6-dev libfwibble-dev libfwibble1 linux-stuff
-0 upgraded, 7 newly installed, 0 to remove and 2 not upgraded.
+The following packages will be upgraded:
+  foreigner:armel
+1 upgraded, 7 newly installed, 0 to remove and 1 not upgraded.
 Inst amdboot (1.0 unstable [amd64])
 Inst doxygen (1.0 unstable [amd64])
+Inst foreigner:armel [0.5] (1.0 unstable [armel])
 Inst libc6 (1.0 unstable [amd64])
 Inst libc6-dev (1.0 unstable [amd64])
 Inst libfwibble1 (1.0 unstable [amd64])
@@ -212,6 +249,7 @@ Inst libfwibble-dev (1.0 unstable [amd64])
 Inst linux-stuff (1.0 unstable [amd64])
 Conf amdboot (1.0 unstable [amd64])
 Conf doxygen (1.0 unstable [amd64])
+Conf foreigner:armel (1.0 unstable [armel])
 Conf libc6 (1.0 unstable [amd64])
 Conf libc6-dev (1.0 unstable [amd64])
 Conf libfwibble1 (1.0 unstable [amd64])
@@ -219,13 +257,17 @@ Conf libfwibble-dev (1.0 unstable [amd64])
 Conf linux-stuff (1.0 unstable [amd64])' aptget build-dep apt -s
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot arm-stuff:armel doxygen libc6 libc6:armel libc6-dev libc6-dev:armel
   libfwibble-dev:armel libfwibble1:armel
-0 upgraded, 9 newly installed, 0 to remove and 2 not upgraded.
+The following packages will be upgraded:
+  cool
+1 upgraded, 9 newly installed, 0 to remove and 1 not upgraded.
 Inst amdboot (1.0 unstable [amd64])
 Inst arm-stuff:armel (1.0 unstable [armel])
+Inst cool [0.5] (1.0 unstable [amd64])
 Inst doxygen (1.0 unstable [amd64])
 Inst libc6 (1.0 unstable [amd64])
 Inst libc6:armel (1.0 unstable [armel])
@@ -235,6 +277,7 @@ Inst libfwibble1:armel (1.0 unstable [armel])
 Inst libfwibble-dev:armel (1.0 unstable [armel])
 Conf amdboot (1.0 unstable [amd64])
 Conf arm-stuff:armel (1.0 unstable [armel])
+Conf cool (1.0 unstable [amd64])
 Conf doxygen (1.0 unstable [amd64])
 Conf libc6 (1.0 unstable [amd64])
 Conf libc6:armel (1.0 unstable [armel])
@@ -273,13 +316,18 @@ Conf libfwibble1 (1.0 unstable [armel])
 Conf libfwibble-dev (1.0 unstable [armel])' aptget build-dep apt -s
 
 testsuccessequal 'Reading package lists...
+Reading package lists...
 Building dependency tree...
 The following NEW packages will be installed:
   amdboot:amd64 doxygen libc6 libc6:amd64 libc6-dev libc6-dev:amd64
   libfwibble-dev:amd64 libfwibble1:amd64 linux-stuff:amd64
-0 upgraded, 9 newly installed, 0 to remove and 2 not upgraded.
+The following packages will be upgraded:
+  cool:amd64 foreigner
+2 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
 Inst amdboot:amd64 (1.0 unstable [amd64])
+Inst cool:amd64 [0.5] (1.0 unstable [amd64])
 Inst doxygen (1.0 unstable [armel])
+Inst foreigner [0.5] (1.0 unstable [armel])
 Inst libc6 (1.0 unstable [armel])
 Inst libc6:amd64 (1.0 unstable [amd64])
 Inst libc6-dev (1.0 unstable [armel])
@@ -288,7 +336,9 @@ Inst libfwibble1:amd64 (1.0 unstable [amd64])
 Inst libfwibble-dev:amd64 (1.0 unstable [amd64])
 Inst linux-stuff:amd64 (1.0 unstable [amd64])
 Conf amdboot:amd64 (1.0 unstable [amd64])
+Conf cool:amd64 (1.0 unstable [amd64])
 Conf doxygen (1.0 unstable [armel])
+Conf foreigner (1.0 unstable [armel])
 Conf libc6 (1.0 unstable [armel])
 Conf libc6:amd64 (1.0 unstable [amd64])
 Conf libc6-dev (1.0 unstable [armel])