fix: invalid URL and 404s in Sphinx index

sphinx/conf.py

@@ -124,6 +124,7 @@
 linkcheck_ignore = [
     "https://docs.jax.dev/en/latest/notebooks/thinking_in_jax.html",
     "https://docs.quantinuum.com/selene",
+    r"https://[a-z0-9-]+\.stackexchange\.com/",
 ]
 
 linkcheck_rate_limit_timeout = 100
@@ -186,5 +187,28 @@ def skip_member(app, what, name, obj, skip, options):
     return None
 
 
+def prune_sourceless_viewcode_modules(app):
+    """Drop viewcode entries for modules whose source could not be read.
+
+    ``sphinx.ext.viewcode`` stores ``False`` for a module it could not read the
+    source of (e.g. the compiled ``builtins`` module) and never writes a page
+    for it, but its ``_modules`` index is built from every module it saw, so it
+    links to pages that do not exist. Pruning them before viewcode's own
+    ``html-collect-pages`` handler (hence the lower priority) keeps the index
+    limited to modules that actually get a page.
+
+    The ``not entry`` test mirrors the skip condition in viewcode's own
+    ``collect_pages``, so exactly the modules it declines to render are removed.
+    Entries for real modules are ``(code, tags, used, refname)`` tuples and are
+    therefore always truthy.
+    """
+    modules = getattr(app.env, "_viewcode_modules", None)
+    if modules:
+        for modname in [name for name, entry in modules.items() if not entry]:
+            del modules[modname]
+    return ()
+
+
 def setup(app):
     app.connect("autodoc-skip-member", skip_member)
+    app.connect("html-collect-pages", prune_sourceless_viewcode_modules, priority=100)

sphinx/getting_started.md

@@ -44,7 +44,7 @@ The intermediate state of the qubits as the circuit progresses is annotated abov
 To implement this circuit in Guppy, we define a Python function with the [`@guppy`](https://docs.quantinuum.com/guppy/api/decorator.html) decorator.
 Since our circuit takes no input, the function does not have to have any parameters.
 Similarly, as the circuit prepares a single-qubit state, we must annotate the function with this as the corresponding return type.
-We can also record the outcome of the mid-circuit measurement for later evaluation using `output`, as this will make it available to the user after we run the simulation. Note that the `measure` function returns a [dedicated `Measurement` type](https://docs.quantinuum.com/guppy/language_guide/measurement).
+We can also record the outcome of the mid-circuit measurement for later evaluation using `output`, as this will make it available to the user after we run the simulation. Note that the `measure` function returns a [dedicated `Measurement` type](https://docs.quantinuum.com/guppy/language_guide/measurement.html).
 
 ```{code-cell} ipython3
 from guppylang import guppy