Adalog: add tests for the handling of dependency cycles

TN: SB20-024
For libadalang/langkit#618

Author: pmderodat

testsuite/tests/adalog/def_cycle/main.adb

@@ -0,0 +1,18 @@
+--  Check that the solver correctly handles an equation that involve a cycle in
+--  variable definitions, when that cycle can be resolved anyway.
+
+with Langkit_Support.Adalog.Main_Support;
+use Langkit_Support.Adalog.Main_Support;
+
+procedure Main is
+   use T_Solver, Refs, Solver_Ifc;
+
+   X : constant Refs.Logic_Var := Create ("X");
+   Y : constant Refs.Logic_Var := Create ("Y");
+   R : constant Relation :=
+     R_All ((Propagate (X, Y),
+             Propagate (Y, X),
+             Assign (X, 1)));
+begin
+   Solve_All (R);
+end Main;

testsuite/tests/adalog/def_cycle/test.out

@@ -0,0 +1,13 @@
+Solving relation:
+All:
+    %Y <- %X
+    %X <- %Y
+    %X <- 1
+
+... without optimizations:
+Solution: [%Y = 1, %X = 1]
+
+... with all optimizations:
+Solution: [%Y = 1, %X = 1]
+
+Done.

testsuite/tests/adalog/def_cycle/test.yaml

@@ -0,0 +1 @@
+driver: adalog

testsuite/tests/adalog/def_cycle_error/main.adb

@@ -0,0 +1,19 @@
+--  Check that the solver correctly handles an equation that involve a cycle in
+--  variable definitions, when that cycle cannot be resolved.
+
+with Langkit_Support.Adalog.Main_Support;
+use Langkit_Support.Adalog.Main_Support;
+
+procedure Main is
+   use T_Solver, Refs, Solver_Ifc;
+
+   X : constant Refs.Logic_Var := Create ("X");
+   Y : constant Refs.Logic_Var := Create ("Y");
+   Z : constant Refs.Logic_Var := Create ("Z");
+   R : constant Relation :=
+     R_All ((Propagate (X, Y),
+             Propagate (Y, Z),
+             Propagate (Z, X)));
+begin
+   Solve_All (R);
+end Main;

testsuite/tests/adalog/def_cycle_error/test.out

@@ -0,0 +1,11 @@
+Solving relation:
+All:
+    %Y <- %X
+    %Z <- %Y
+    %X <- %Z
+
+... without optimizations:
+
+... with all optimizations:
+
+Done.

testsuite/tests/adalog/def_cycle_error/test.yaml

@@ -0,0 +1 @@
+driver: adalog