P1972R0 US105 Check satisfaction of constraints for non-templates whe…

source/expressions.tex

@@ -675,12 +675,6 @@
 function.\footnote{This conversion never applies to non-static member functions because an
 lvalue that refers to a non-static member function cannot be obtained.}
 
-\pnum
-\begin{note}
-See~\ref{over.over} for additional rules for the case where the function
-is overloaded.
-\end{note}
-
 \rSec2[conv.rval]{Temporary materialization conversion}
 \indextext{conversion!temporary materialization}%
 
@@ -1316,12 +1310,14 @@
 \end{note}
 
 \pnum
-A program that refers
-explicitly or implicitly
-to a function with a trailing \grammarterm{requires-clause}
+For an \grammarterm{id-expression} that denotes an overload set,
+overload resolution is performed
+to select a unique function~(\ref{over.match}, \ref{over.over}).
+\begin{note}
+A program cannot refer to a function
+with a trailing \grammarterm{requires-clause}
 whose \grammarterm{constraint-expression} is not satisfied,
-other than to declare it,
-is ill-formed.
+because such functions are never selected by overload resolution.
 \begin{example}
 \begin{codeblock}
 template<typename T> struct A {
@@ -1340,6 +1336,7 @@
 even though
 \tcode{f} is an unevaluated operand\iref{expr.prop}.
 \end{example}
+\end{note}
 
 \rSec3[expr.prim.id.unqual]{Unqualified names}
 
@@ -2903,7 +2900,13 @@
 A function call is a postfix expression followed by parentheses
 containing a possibly empty, comma-separated list of
 \grammarterm{initializer-clause}{s} which
-constitute the arguments to the function. The postfix expression shall
+constitute the arguments to the function.
+\begin{note}
+If the postfix expression is a function or member function name,
+the appropriate function and the validity of the call
+are determined according to the rules in~\ref{over.match}.
+\end{note}
+The postfix expression shall
 have function type or function pointer type.
 For a call to a non-member function or to a static member function,
 the postfix expression shall either be an lvalue that refers to a
@@ -2927,9 +2930,7 @@
 \end{note}
 
 \pnum
-If a function or member function name is used,
-the appropriate function and the validity of the call are determined
-according to the rules in~\ref{over.match}. If the selected
+If the selected
 function is non-virtual, or if the \grammarterm{id-expression} in the class
 member access expression is a \grammarterm{qualified-id}, that function is
 called. Otherwise, its final overrider\iref{class.virtual} in the dynamic type
@@ -4246,10 +4247,10 @@
 
 \pnum
 \indextext{overloaded function!address of}%
+\begin{note}
 The address of an overloaded function\iref{over} can be taken
 only in a context that uniquely determines which version of the
 overloaded function is referred to (see~\ref{over.over}).
-\begin{note}
 Since the context might determine whether the operand is a static or
 non-static member function, the context can also affect whether the
 expression has type ``pointer to function'' or ``pointer to member

source/overloading.tex

@@ -3141,19 +3141,12 @@
 \indextext{overloaded function!address of}
 
 \pnum
-A use of an overloaded function name without arguments is resolved
-in certain contexts to a function, a pointer to function or a pointer to
-member function for a specific function from the overload set.
-A function template name is considered to name a set of overloaded functions
-in such contexts.
-A function with type \tcode{F} is selected for the function type \tcode{FT}
-of the target type required in the context if \tcode{F}
-(after possibly applying the function pointer conversion\iref{conv.fctptr})
-is identical to \tcode{FT}.
-\begin{note}
-That is, the class of which the function is a member is ignored when matching a
-pointer-to-member-function type.
-\end{note}
+A use of a function name without arguments is resolved to
+a function, a pointer to function, or a pointer to member function
+for a specific function
+that is chosen from a set of selected functions
+determined based on the target type required in the context (if any),
+as described below.
 The target can be
 \begin{itemize}
 \item
@@ -3174,25 +3167,33 @@
 a non-type
 \grammarterm{template-parameter}\iref{temp.arg.nontype}.
 \end{itemize}
-
-The overloaded function name can be preceded by the
-\tcode{\&}
-operator.
-An overloaded function name shall not be used without arguments in contexts
-other than those listed.
+The function name can be preceded by the \tcode{\&} operator.
 \begin{note}
-Any redundant set of parentheses surrounding the overloaded function name is
+Any redundant set of parentheses surrounding the function name is
 ignored\iref{expr.prim.paren}.
 \end{note}
 
 \pnum
-If the name is a function template, template argument deduction is
-done\iref{temp.deduct.funcaddr}, and if the argument deduction succeeds,
+If there is no target, all non-template functions named are selected.
+Otherwise, a non-template function with type \tcode{F}
+is selected for the function type \tcode{FT} of the target type
+if \tcode{F}
+(after possibly applying the function pointer conversion\iref{conv.fctptr})
+is identical to \tcode{FT}.
+\begin{note}
+That is, the class of which the function is a member is ignored when matching a
+pointer-to-member-function type.
+\end{note}
+
+\pnum
+For each function template designated by the name,
+template argument deduction is done\iref{temp.deduct.funcaddr}, and
+if the argument deduction succeeds,
 the
 resulting template argument list is
 used to generate a single
 function template specialization,
-which is added to the set of overloaded functions
+which is added to the set of selected functions
 considered.
 \begin{note}
 As described in~\ref{temp.arg.explicit}, if deduction fails and the
@@ -3212,6 +3213,7 @@
 reference to function type.
 Non-static member functions match targets of
 pointer-to-member-function type.
+%% FIXME: Should this only apply after the eliminations in the next paragraph?
 If a non-static member function is selected, the reference to the overloaded
 function name is required to have the form of a pointer to member as
 described in~\ref{expr.unary.op}.

source/templates.tex

@@ -7802,13 +7802,15 @@
 \pnum
 Template arguments can be deduced from the type specified when taking
 the address of an overloaded function\iref{over.over}.
-The function template's function type and the specified type
+If there is a target,
+the function template's function type and the target type
 are used as the types of
 \tcode{P}
 and
 \tcode{A},
 and the deduction is done as
 described in~\ref{temp.deduct.type}.
+Otherwise, deduction is performed with empty sets of types P and A.
 
 \pnum
 A placeholder type\iref{dcl.spec.auto} in the return type of a