Errors that occur while constructing a specific should be tied back to
the facet type being identified. We don't have an InstId for the facet
type during identify, so provide the means to Stringify a FacetTypeId.
Depends on https://github.com/carbon-language/carbon-lang/pull/6435
Once a concrete result has been found, it's not legal to write an `impl`
that would change the concrete result afterward.
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Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Use it to stringify associated constant values in diagnostics. In
passing, add missing support for stringifying bool literals. Note that
there are some cases that it doesn't stringify properly, but that's not
new here; such cases could already be observed when stringifying generic
arguments.
Dana Jansens
Jon Ross-PerkinsandRichard Smith