Merge pull request swiftlang#36588 from guitard0g/const_eval_range_support

Extend compile-time constantness check to support constant Ranges

Author: Josh Learn

lib/Sema/ConstantnessSemaDiagnostics.cpp

@@ -105,7 +105,7 @@ static Expr *checkConstantness(Expr *expr) {
   expressionsToCheck.push_back(expr);
   while (!expressionsToCheck.empty()) {
     Expr *expr = expressionsToCheck.pop_back_val();
-    // Lookthrough identity_expr, tuple and inject_into_optional expressions.
+    // Lookthrough identity_expr, tuple, binary_expr and inject_into_optional expressions.
     if (IdentityExpr *identityExpr = dyn_cast<IdentityExpr>(expr)) {
       expressionsToCheck.push_back(identityExpr->getSubExpr());
       continue;
@@ -115,6 +115,10 @@ static Expr *checkConstantness(Expr *expr) {
         expressionsToCheck.push_back(element);
       continue;
     }
+    if (BinaryExpr *binaryExpr = dyn_cast<BinaryExpr>(expr)) {
+      expressionsToCheck.push_back(binaryExpr->getArg());
+      continue;
+    }
     if (InjectIntoOptionalExpr *optionalExpr =
             dyn_cast<InjectIntoOptionalExpr>(expr)) {
       expressionsToCheck.push_back(optionalExpr->getSubExpr());

test/Sema/diag_constantness_check.swift

@@ -328,3 +328,19 @@ func testAtomicOrderingConstantness(
   _ = atomicInt.load(ordering: myOrder)
     // expected-error@-1 {{ordering argument must be a static method or property of 'AtomicLoadOrdering'}}
 }
+
+// Test that the check can handle ranges
+@_semantics("oslog.requires_constant_arguments")
+func constantRange(x: Range<Int>) {}
+
+@_semantics("oslog.requires_constant_arguments")
+func constantClosedRange(x: ClosedRange<Int>) {}
+
+func testConstantRange(x: Int) {
+  constantRange(x: 0..<5)
+  constantRange(x: 0..<x)
+    // expected-error@-1 {{argument must be an integer literal}}
+  constantClosedRange(x: 0...10)
+  constantClosedRange(x: x...10)
+    // expected-error@-1 {{argument must be an integer literal}}
+}