[CPyCppyy] Correctly propagate template argument name errors #20976
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guitargeek
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vepadulano
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I think the changes are good, but could you also add a test with an example of the error being raised?
In case the `Utility::ConstructTemplateArgs()` method fails to create
the C++ template names, it sets a useful Python exception that is
unfortunately not propagated, because the calling code in
`TemplateProxy.cxx` is ignoring it. This is fixed in this commit.
The place where the error is set is also moved from
`Utility::ConstructTemplateArgs()` to the actual implementation:
`AddTypeName()`. This means the error is set by the function that
actually has the context of the error, which is conceptually cleaner and
will allow us also to set more detailed errors for different failure
modes of `AddTypeName()`.
A unit test is also implemented.
Demo code:
```python
import cppyy
cppyy.cppdef("""
template<class T>
class Foo {};
template<class T, class Y=void>
auto make_foo () { return Foo<T>{}; }
template<class T, class Y=void>
auto make_foo (T x) { return Foo<T>{}; }
""")
cppyy.gbl.make_foo[set(), list()]()
```
Before:
```
cppyy.gbl.make_foo[set(), list()]()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
TypeError: Could not find "make_foo" (set cppyy.set_debug() for C++ errors):
Template method resolution failed:
Failed to instantiate "make_foo()"
Failed to instantiate "make_foo()"
```
After:
```
cppyy.gbl.make_foo[set(), list()]()
~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
TypeError: could not construct C++ name from template argument set()
```
Note: this work is orthogonal to the rebase of `cppyy` on CppInterOp.
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LGTM, feel free to merge once the CI is green
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In case the
Utility::ConstructTemplateArgs()method fails to create the C++ template names, it sets a useful Python exception that is unfortunately not propagated, because the calling code inTemplateProxy.cxxis ignoring it. This is fixed in this commit.The place where the error is set is also moved from
Utility::ConstructTemplateArgs()to the actual implementation:AddTypeName(). This means the error is set by the function that actually has the context of the error, which is conceptually cleaner and will allow us also to set more detailed errors for different failure modes ofAddTypeName().Demo code:
Before:
After:
Note: this work is orthogonal to the rebase of
cppyyon CppInterOp.