Fix false-positive missing enum2int warning

Fixes #887

changes.rst

@@ -24,6 +24,8 @@ Bug fixes:
    comprehensions, leading to an internal error (:bugref:`879`).
 -  Fix false-positive implicit enum coercion warnings when calling ``card`` and
    some inequality operators.
+-  Fix false-positive implicit enum coercion warnings for calls with
+   comprehension arguments (:bugref:`887`).
 -  Recursively type check type-insts of variable declarations and function
    items.
 

lib/typecheck.cpp

@@ -3034,7 +3034,12 @@ class Typer {
         }
         Type t_before = Expression::type(c_e);
         Type t = fi->argtype(_env, args, i).elemType(_env);
+        // Call to enum2int would have been removed when processing the comprehension,
+        // so don't warn here
+        bool warnImplicitEnum2Int = _env.warnImplicitEnum2Int;
+        _env.warnImplicitEnum2Int = false;
         c_e = add_coercion(_env, _model, c_e, t)();
+        _env.warnImplicitEnum2Int = warnImplicitEnum2Int;
         Type t_after = Expression::type(c_e);
         if (t_before != t_after) {
           if (indexTuple != nullptr) {

tests/spec/unit/regression/github_887.mzn

@@ -0,0 +1,11 @@
+/***
+!Test
+solvers: [gecode]
+options:
+  -Werror: true
+expected: !Result
+  status: SATISFIED
+***/
+
+enum Foo = {A};
+output show({enum2int(x) | x in Foo});