Merge remote-tracking branch 'origin/topic/bbannier/issue-1981'

CHANGES

@@ -1,3 +1,17 @@
+1.13.0-dev.115 | 2025-03-06 12:00:38 +0100
+
+  * GH-1981: Reject function overloads which only differ in default'd parameters. (Benjamin Bannier, Corelight)
+
+    Resolution of calls to functions who's signatures differ only in
+    defaulted parameters behaved non-intuitively in that when given with
+    less than the maximum possible number of parameters we resolved to the
+    overload with most parameters.
+
+    With this patch we reject such overloads where the only difference is in
+    defaulted parameters.
+
+    Closes #1981.
+
 1.13.0-dev.113 | 2025-03-03 17:39:36 +0100
 
   * GH-1983: Audit links in README. (Benjamin Bannier, Corelight)

VERSION

@@ -1 +1 @@
-1.13.0-dev.113
+1.13.0-dev.115

hilti/toolchain/include/ast/types/function.h

@@ -110,8 +110,6 @@ inline bool areEquivalent(Function* f1, Function* f2) {
 }
 
 /** Returns true if the provided function types can be valid overloads of each other. */
-inline bool isValidOverload(Function* f1, Function* f2) {
-    return type::same(f1->result(), f2->result()) || ! areEquivalent(f1->parameters(), f2->parameters());
-}
+bool isValidOverload(Function* f1, Function* f2);
 
 } // namespace hilti::type

hilti/toolchain/src/ast/types/function.cc

@@ -1,6 +1,9 @@
 // Copyright (c) 2020-now by the Zeek Project. See LICENSE for details.
 
-#include <hilti/ast/types/function.h>
+#include "hilti/ast/types/function.h"
+
+#include <algorithm>
+#include <iterator>
 
 using namespace hilti;
 
@@ -23,3 +26,17 @@ bool type::Function::isResolved(node::CycleDetector* cd) const {
 
     return true;
 }
+
+bool type::isValidOverload(Function* f1, Function* f2) {
+    const auto& params1 = f1->parameters();
+    const auto& params2 = f2->parameters();
+
+    auto non_defaulted = [](const node::Set<function::Parameter>& p) {
+        node::Set<function::Parameter> r;
+        std::copy_if(p.begin(), p.end(), std::back_inserter(r), [](function::Parameter* p) { return ! p->default_(); });
+        return r;
+    };
+
+    return type::same(f1->result(), f2->result()) ||
+           (! areEquivalent(params1, params2) && ! areEquivalent(non_defaulted(params1), non_defaulted(params2)));
+}

tests/Baseline/hilti.validation.duplicate-5/output

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[error] <...>/duplicate.hlt:12:1-14:1: 'fun' is not a valid overload; previous definition in <...>/duplicate.hlt:8:1-10:1
+[error] hiltic: aborting after errors

tests/hilti/validation/duplicate.hlt

@@ -50,3 +50,23 @@ global s2 = succeed(1);
 # Force failure to get output
 assert s1 == s2: "%d == %d" % (s1, s2);
 }
+
+# @TEST-START-NEXT
+
+module foo {
+
+import hilti;
+
+# Overloads which only differ in defaulted parameters are not allowed. This is
+# roughly in line with the overloads C++ allows.
+function uint<8> fun(uint<8> a) {
+    return uint8(1);
+}
+
+function uint<16> fun(uint<8> a, uint<8> b = uint8(0)) {
+    return uint16(2);
+}
+
+hilti::print(fun(uint8(1)));
+
+}