updating model with help from @tgamblin

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

lib/spack/spack/solver/logic/concretize.lp

@@ -38,6 +38,7 @@ version_satisfies(Package, Constraint)
 #defined preferred_version_declared/3.
 #defined version_satisfies/3.
 
+
 %-----------------------------------------------------------------------------
 % Spec conditions and imposed constraints
 %
@@ -97,7 +98,6 @@ do_not_impose(ID) :-
 % They're only triggered if the associated dependnecy condition holds.
 depends_on(Package, Dependency, Type)
  :- dependency_holds(Package, Dependency, Type),
-    dependency_checks_hold(Package, Dependency, Type),
     not virtual(Dependency).
 
 % every root must be a node
@@ -123,6 +123,24 @@ path(Parent, Descendant) :- path(Parent, A), depends_on(A, Descendant).
 #defined dependency_type/2.
 #defined dependency_condition/3.
 
+%-----------------------------------------------------------------------------
+% ABI Compatibility
+%-----------------------------------------------------------------------------
+
+% compatibility is defined as the absence of any incompatibilities
+compatible(Package, Dependency) :-
+        node(Package),
+        node(Dependency),
+        version(Package, V1),
+        version(Dependency, V2),
+        not incompatible(Package, V1, Dependency, V2).
+
+#defined incompatible/4.
+
+% Do not admit models with ABI-incompatible dependencies
+:- depends_on(Package, Dependency), not compatible(Package, Dependency).
+
+
 %-----------------------------------------------------------------------------
 % Conflicts
 %-----------------------------------------------------------------------------

lib/spack/spack/solver/logic/symbols.lp

@@ -76,69 +76,32 @@ defined_symbol(Package, Version, Symbol)
     :- defined_symbol(Package, Version, Symbol, _, _).
 
 
-% This is the main "entry" function from concretize.lp
-% dependency checks hold if
-dependency_checks_hold(Package, Dependency, Type)
-
-    % the dependency holds and
-    :- dependency_holds(Package, Dependency, Type),
-
-    % there are no check failures
-    not check_failure(Package, Dependency, Type).
-
-
-% the dependency checks fail
-check_failure(Package, Dependency, Type)
+% a package and dependency are linkable if
+linkable(Package, Dependency)
 
-    % if both the package and dependency are nodes
+    % The package and dependency are nodes in the graph
     :- node(Package),
     node(Dependency),
 
-    % they have set versions
-    version(Package, Version),
-    version(Dependency, DependencyVersion),
-
-    % and the symbols for those versions don't match
-    not mismatch(Package, Version, Dependency, DependencyVersion, Type),
-
-    % type is unsafe if we don't add this.
-    Type == "link".
-
+    % And the dependency holds
+    dependency_holds(Package, Dependency, _).
+
 
-% There is a mismatch for a package and dependency if:
-mismatch(Package, Version, Dependency, DependencyVersion, Type)
+% A package and dependency are incompatible if:
+incompatible(Package, V1, Dependency, V2)
 
     % they are linkable
     :- linkable(Package, Dependency),
 
     % The package and dependency each have their own version
-    version(Package, Version),
-    version(Dependency, DependencyVersion),
+    version(Package, V1),
+    version(Dependency, V2),
 
     % The package has an undefined symbol
-    undefined_symbol(Package, Version, Symbol),
+    undefined_symbol(Package, V1, Symbol),
 
     % the package depends on the dependency
-    depends_on(Package, Dependency, Type),
+    depends_on(Package, Dependency),
 
     % and the symbol is not defined for the dependency
-    not defined_symbol(Dependency, DependencyVersion, Symbol).
-
-
-% a package and dependency are linkable if
-linkable(Package, Dependency)
-
-    % The package and dependency are nodes in the graph
-    :- node(Package),
-    node(Dependency),
-
-    % And the dependency holds
-    dependency_holds(Package, Dependency, _).
-
-% transitive
-% I don't know how we can have two versions here?
-defined_symbol(Package, Version, Symbol)
-    :- depends_on(Package, Dependency, Type), defined_symbol(Dependency, Version, Symbol).
-
-:- depends_on(Package, Dependency, _),
-   not dependency_checks_hold(Package, Dependency, _).
+    not defined_symbol(Dependency, V2, Symbol).