From Jason Turner

[temp.deduct.conv]

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  #### Deducing conversion function template arguments <a id="temp.deduct.conv">[[temp.deduct.conv]]</a>
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  Template argument deduction is done by comparing the return type of the
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- conversion function template (call it `P`) with the type that is
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- required as the result of the conversion (call it `A`; see 
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- [[dcl.init]], [[over.match.conv]], and [[over.match.ref]] for the
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- determination of that type) as described in  [[temp.deduct.type]].
 
 
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  If `P` is a reference type, the type referred to by `P` is used in place
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  of `P` for type deduction and for any further references to or
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  transformations of `P` in the remainder of this subclause.
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@@ -24,22 +26,20 @@ If `A` is not a reference type:
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  If `A` is a cv-qualified type, the top-level cv-qualifiers of `A`’s type
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  are ignored for type deduction. If `A` is a reference type, the type
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  referred to by `A` is used for type deduction.
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  In general, the deduction process attempts to find template argument
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- values that will make the deduced `A` identical to `A`. However, there
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- are four cases that allow a difference:
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- - If the original `A` is a reference type, `A` can be more cv-qualified
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- than the deduced `A` (i.e., the type referred to by the reference).
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- - If the original `A` is a function pointer type, `A` can be “pointer to
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- function” even if the deduced `A` is “pointer to `noexcept` function”.
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- - If the original `A` is a pointer-to-member-function type, `A` can be
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- “pointer to member of type function” even if the deduced `A` is
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- “pointer to member of type `noexcept` function”.
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- - The deduced `A` can be another pointer or pointer-to-member type that
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- can be converted to `A` via a qualification conversion.
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- These alternatives are considered only if type deduction would otherwise
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- fail. If they yield more than one possible deduced `A`, the type
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- deduction fails.
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  #### Deducing conversion function template arguments <a id="temp.deduct.conv">[[temp.deduct.conv]]</a>
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  Template argument deduction is done by comparing the return type of the
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+ conversion function template (call it `P`) with the type specified by
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+ the *conversion-type-id* of the *conversion-function-id* being looked up
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+ (call it `A`) as described in  [[temp.deduct.type]]. If the
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+ *conversion-function-id* is constructed during overload resolution
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+ [[over.match.funcs]], the rules in the remainder of this subclause
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+ apply.
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  If `P` is a reference type, the type referred to by `P` is used in place
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  of `P` for type deduction and for any further references to or
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  transformations of `P` in the remainder of this subclause.
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  If `A` is a cv-qualified type, the top-level cv-qualifiers of `A`’s type
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  are ignored for type deduction. If `A` is a reference type, the type
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  referred to by `A` is used for type deduction.
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  In general, the deduction process attempts to find template argument
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+ values that will make the deduced `A` identical to `A`. However, certain
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+ attributes of `A` may be ignored:
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+ - If the original `A` is a reference type, any cv-qualifiers of `A`
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+ (i.e., the type referred to by the reference).
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+ - If the original `A` is a function pointer or
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+ pointer-to-member-function type with a potentially-throwing exception
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+ specification [[except.spec]], the exception specification.
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+ - Any cv-qualifiers in `A` that can be restored by a qualification
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+ conversion.
 
 
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+ These attributes are ignored only if type deduction would otherwise
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+ fail. If ignoring them allows more than one possible deduced `A`, the
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+ type deduction fails.
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