Exempt "compilers" and "runtimes" from default requirements

lib/spack/spack/solver/asp.py

@@ -2732,7 +2732,7 @@ def visit(node):
                                 arg = ast_sym(ast_sym(term.atom).arguments[0])
                                 symbol = AspFunction(name)(arg.string)
                                 self.assumptions.append((parse_term(str(symbol)), True))
-                                self.gen.asp_problem.append(f"{symbol}.\n")
+                                self.gen.asp_problem.append(f"{{ {symbol} }}.\n")
 
         path = os.path.join(parent_dir, "concretize.lp")
         parse_files([path], visit)

lib/spack/spack/solver/concretize.lp

@@ -315,18 +315,21 @@ possible_version_weight(node(ID, Package), Weight)
 
 % If there is at least a version that satisfy the constraint, impose a lower
 % bound on the choice rule to avoid false positives with the error below
-1 { attr("version", node(ID, Package), Version) : pkg_fact(Package, version_satisfies(Constraint, Version)) }
+{ attr("version", node(ID, Package), Version) : pkg_fact(Package, version_satisfies(Constraint, Version)) }
   :- attr("node_version_satisfies", node(ID, Package), Constraint),
-     pkg_fact(Package, version_satisfies(Constraint, _)),
+     pkg_fact(Package, version_satisfies(Constraint, _)).
-     internal_error("must choose a single version to satisfy version constraints").
 
 % More specific error message if the version cannot satisfy some constraint
 % Otherwise covered by `no_version_error` and `versions_conflict_error`.
-error(10, "Cannot satisfy '{0}@{1}'", Package, Constraint)
+error(1, "Cannot satisfy '{0}@{1}'", Package, Constraint)
   :- attr("node_version_satisfies", node(ID, Package), Constraint),
      attr("version", node(ID, Package), Version),
      not pkg_fact(Package, version_satisfies(Constraint, Version)).
 
+error(10, "Cannot satisfy '{0}@{1}'", Package, Constraint)
+  :- attr("node_version_satisfies", node(ID, Package), Constraint),
+     not attr("version", node(ID, Package), _).
+
 attr("node_version_satisfies", node(ID, Package), Constraint)
   :- attr("version", node(ID, Package), Version),
      pkg_fact(Package, version_satisfies(Constraint, Version)).
@@ -1234,7 +1237,7 @@ propagated_flag(node(PackageID, Package), node_flag(FlagType, Flag, FlagGroup, S
 attr("node_flag", PackageNode, NodeFlag) :- propagated_flag(PackageNode, NodeFlag, _).
 
 % Cannot propagate the same flag from two distinct sources
-error(100, "{0} and {1} cannot both propagate compiler flags '{2}' to {3}", Source1, Source2, Package, FlagType) :-
+error(100, "{0} and {1} cannot both propagate compiler flags '{2}' to {3}", Source1, Source2, FlagType, Package) :-
   propagated_flag(node(ID, Package), node_flag(FlagType, _, _, _), node(_, Source1)),
   propagated_flag(node(ID, Package), node_flag(FlagType, _, _, _), node(_, Source2)),
   Source1 < Source2.
@@ -1267,7 +1270,7 @@ has_built_packages() :- build(X), not external(X).
 
 % FIXME (compiler as nodes): is this version constraint always required and better than the callback?
 % "gcc-runtime" and the "gcc" it depends on must be at the same version
-% attr("version", node(X, "gcc"), Version) :-
+% attr("version", node(Y, "gcc"), Version) :-
 %   attr("version", node(X, "gcc-runtime"), Version),
 %   attr("depends_on", node(X, "gcc-runtime"), node(Y, "gcc"), "build").
 

var/spack/repos/builtin.mock/packages/gcc/package.py

@@ -12,9 +12,10 @@ class Gcc(CompilerPackage, Package):
     homepage = "http://www.example.com"
     url = "http://www.example.com/gcc-1.0.tar.gz"
 
-    version("1.0", md5="0123456789abcdef0123456789abcdef")
+    version("14.0", md5="abcdef0123456789abcdef0123456789")
-    version("2.0", md5="abcdef0123456789abcdef0123456789")
     version("3.0", md5="def0123456789abcdef0123456789abc")
+    version("2.0", md5="abcdef0123456789abcdef0123456789")
+    version("1.0", md5="0123456789abcdef0123456789abcdef")
 
     variant(
         "languages",
@@ -28,6 +29,8 @@ class Gcc(CompilerPackage, Package):
     provides("cxx", when="languages=c++")
     provides("fortran", when="languages=fortran")
 
+    depends_on("c", type="build")
+
     c_names = ["gcc"]
     cxx_names = ["g++"]
     fortran_names = ["gfortran"]