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Improve "No constructor matches given arguments" message with more details #1143

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Merged
merged 1 commit into from
May 14, 2020
Merged

Improve "No constructor matches given arguments" message with more details #1143

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11 changes: 10 additions & 1 deletion src/runtime/constructorbinder.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System;
using System.Reflection;
using System.Text;

namespace Python.Runtime
{
Expand Down Expand Up @@ -93,7 +94,15 @@ internal object InvokeRaw(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info)

if (binding == null)
{
Exceptions.SetError(Exceptions.TypeError, "no constructor matches given arguments");
var errorMessage = new StringBuilder("No constructor matches given arguments");
if (info != null && info.IsConstructor && info.DeclaringType != null)
{
errorMessage.Append(" for ").Append(info.DeclaringType.Name);
}

errorMessage.Append(": ");
AppendArgumentTypes(to: errorMessage, args);
Exceptions.SetError(Exceptions.TypeError, errorMessage.ToString());
return null;
}
}
Expand Down
59 changes: 36 additions & 23 deletions src/runtime/methodbinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -599,6 +599,40 @@ internal virtual IntPtr Invoke(IntPtr inst, IntPtr args, IntPtr kw, MethodBase i
return Invoke(inst, args, kw, info, null);
}

protected static void AppendArgumentTypes(StringBuilder to, IntPtr args)
{
long argCount = Runtime.PyTuple_Size(args);
to.Append("(");
for (long argIndex = 0; argIndex < argCount; argIndex++)
{
var arg = Runtime.PyTuple_GetItem(args, argIndex);
if (arg != IntPtr.Zero)
{
var type = Runtime.PyObject_Type(arg);
if (type != IntPtr.Zero)
{
try
{
var description = Runtime.PyObject_Unicode(type);
if (description != IntPtr.Zero)
{
to.Append(Runtime.GetManagedString(description));
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If GetManagedString fails, you leak description

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Ah, but I see that is not your doing but was already in the code...

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@filmor it is still my doing :-D

Runtime.XDecref(description);
}
}
finally
{
Runtime.XDecref(type);
}
}
}

if (argIndex + 1 < argCount)
to.Append(", ");
}
to.Append(')');
}

internal virtual IntPtr Invoke(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, MethodInfo[] methodinfo)
{
Binding binding = Bind(inst, args, kw, info, methodinfo);
Expand All @@ -613,29 +647,8 @@ internal virtual IntPtr Invoke(IntPtr inst, IntPtr args, IntPtr kw, MethodBase i
value.Append($" for {methodinfo[0].Name}");
}

long argCount = Runtime.PyTuple_Size(args);
value.Append(": (");
for(long argIndex = 0; argIndex < argCount; argIndex++) {
var arg = Runtime.PyTuple_GetItem(args, argIndex);
if (arg != IntPtr.Zero) {
var type = Runtime.PyObject_Type(arg);
if (type != IntPtr.Zero) {
try {
var description = Runtime.PyObject_Unicode(type);
if (description != IntPtr.Zero) {
value.Append(Runtime.GetManagedString(description));
Runtime.XDecref(description);
}
} finally {
Runtime.XDecref(type);
}
}
}

if (argIndex + 1 < argCount)
value.Append(", ");
}
value.Append(')');
value.Append(": ");
AppendArgumentTypes(to: value, args);
Exceptions.SetError(Exceptions.TypeError, value.ToString());
return IntPtr.Zero;
}
Expand Down