Fix doctool merges when method signatures don't match

If methods signature did not match, documentation is not merged. This is
a considerable source of annoyance for contributors and it happened as
a result of #4533, otherwise the documentation for constructors would
not be properly merged.

This PR modifies the logic introduced to only do the signature test on
constructors and operators (which are the only types of members that can repeat).

editor/doc_tools.cpp

@@ -64,35 +64,42 @@ void DocTools::merge_from(const DocTools &p_data) {
 				if (cf.methods[j].name != m.name) {
 					continue;
 				}
-				if (cf.methods[j].arguments.size() != m.arguments.size()) {
-					continue;
-				}
-				// since polymorphic functions are allowed we need to check the type of
-				// the arguments so we make sure they are different.
-				int arg_count = cf.methods[j].arguments.size();
-				Vector<bool> arg_used;
-				arg_used.resize(arg_count);
-				for (int l = 0; l < arg_count; ++l) {
-					arg_used.write[l] = false;
-				}
-				// also there is no guarantee that argument ordering will match, so we
-				// have to check one by one so we make sure we have an exact match
-				for (int k = 0; k < arg_count; ++k) {
+
+				const char *operator_prefix = "operator "; // Operators use a space at the end, making this prefix an invalid identifier (and differentiating from methods).
+
+				if (cf.methods[j].name == c.name || cf.methods[j].name.begins_with(operator_prefix)) {
+					// Since constructors and operators can repeat, we need to check the type of
+					// the arguments so we make sure they are different.
+
+					if (cf.methods[j].arguments.size() != m.arguments.size()) {
+						continue;
+					}
+
+					int arg_count = cf.methods[j].arguments.size();
+					Vector<bool> arg_used;
+					arg_used.resize(arg_count);
 					for (int l = 0; l < arg_count; ++l) {
-						if (cf.methods[j].arguments[k].type == m.arguments[l].type && !arg_used[l]) {
-							arg_used.write[l] = true;
-							break;
+						arg_used.write[l] = false;
+					}
+					// also there is no guarantee that argument ordering will match, so we
+					// have to check one by one so we make sure we have an exact match
+					for (int k = 0; k < arg_count; ++k) {
+						for (int l = 0; l < arg_count; ++l) {
+							if (cf.methods[j].arguments[k].type == m.arguments[l].type && !arg_used[l]) {
+								arg_used.write[l] = true;
+								break;
+							}
 						}
 					}
-				}
-				bool not_the_same = false;
-				for (int l = 0; l < arg_count; ++l) {
-					if (!arg_used[l]) { // at least one of the arguments was different
-						not_the_same = true;
+					bool not_the_same = false;
+					for (int l = 0; l < arg_count; ++l) {
+						if (!arg_used[l]) { // at least one of the arguments was different
+							not_the_same = true;
+						}
+					}
+					if (not_the_same) {
+						continue;
 					}
-				}
-				if (not_the_same) {
-					continue;
 				}
 
 				const DocData::MethodDoc &mf = cf.methods[j];