[std] Rephrase notes containing 'must'

Fixes ISO/CS 037 (C++23 DIS).

Author: jensmaurer

source/algorithms.tex

@@ -335,7 +335,7 @@
 another function invocation is specified to synchronize with it,
 and if it is not a memory allocation or deallocation function.
 \begin{note}
-Implementations must ensure that internal synchronization
+Implementations are expected to ensure that internal synchronization
 inside standard library functions does not prevent forward progress
 when those functions are executed by threads of execution
 with weakly parallel forward progress guarantees.

source/basic.tex

@@ -585,8 +585,8 @@
 \end{example}
 \begin{note}
 The rules for declarations and expressions
-describe in which contexts complete class types are required. A class
-type \tcode{T} must be complete if:
+describe in which contexts complete class types are required.
+The program is ill-formed unless a class type \tcode{T} is complete if:
 \begin{itemize}
 \item an object of type \tcode{T} is defined\iref{basic.def}, or
 \item a non-static class data member of type \tcode{T} is
@@ -4207,10 +4207,10 @@
 struct D : virtual B { char c; };
 \end{codeblock}
 
-When \tcode{D} is the type of a complete object, it will have a subobject of
-type \tcode{B}, so it must be aligned appropriately for a \tcode{\keyword{long} \keyword{double}}.
+When \tcode{D} is the type of a complete object, it has a subobject of
+type \tcode{B}, so it is aligned appropriately for a \tcode{\keyword{long} \keyword{double}}.
 If \tcode{D} appears as a subobject of another object that also has \tcode{B}
-as a virtual base class, the \tcode{B} subobject might be part of a different
+as a virtual base class, the \tcode{B} subobject can be part of a different
 subobject, reducing the alignment requirements on the \tcode{D} subobject.
 \end{example}
 The result of the \keyword{alignof} operator reflects the alignment
@@ -6368,7 +6368,7 @@
 \begin{note}
 The value observed by a load of an atomic depends on the ``happens
 before'' relation, which depends on the values observed by loads of atomics.
-The intended reading is that there must exist an
+The intended reading is that there exists an
 association of atomic loads with modifications they observe that, together with
 suitably chosen modification orders and the ``happens before'' relation derived
 as described above, satisfy the resulting constraints as imposed here.

source/classes.tex

@@ -435,9 +435,10 @@
 class A * A;
 \end{codeblock}
 first specifies \tcode{A} to be the name of a class and then redefines
-it as the name of a pointer to an object of that class. This means that
-the elaborated form \keyword{class} \tcode{A} must be used to refer to the
-class. Such artistry with names can be confusing and is best avoided.
+it as the name of a pointer to an object of that class.
+This means references to the class are ill-formed
+unless the elaborated form \keyword{class} \tcode{A} is used.
+Such artistry with names can be confusing and is best avoided.
 \end{note}
 
 \pnum
@@ -2226,7 +2227,7 @@
 \end{codeblock}
 \end{example}
 \begin{note}
-An explicit destructor call must always be written using
+An explicit destructor call is always written using
 a member access operator\iref{expr.ref} or a \grammarterm{qualified-id}\iref{expr.prim.id.qual};
 in particular, the
 \grammarterm{unary-expression}
@@ -3107,9 +3108,10 @@
 default constructor\iref{class.default.ctor},
 copy constructor, move constructor\iref{class.copy.ctor},
 copy assignment operator, move assignment operator\iref{class.copy.assign},
-or destructor\iref{class.dtor}, the corresponding member function
-of the union must be user-provided or it will
-be implicitly deleted\iref{dcl.fct.def.delete} for the union.
+or destructor\iref{class.dtor},
+the corresponding member function of the union
+will be implicitly deleted\iref{dcl.fct.def.delete}
+unless it is user-provided.
 \begin{example}
 Consider the following union:
 \begin{codeblock}
@@ -3123,8 +3125,8 @@
 member functions, \tcode{U} will have an implicitly deleted default constructor,
 copy/move constructor,
 copy/move assignment operator, and destructor.
-To use \tcode{U}, some or all of these member functions
-must be user-provided.
+A use \tcode{U} is ill-formed
+unless some or all of these member functions are user-provided.
 \end{example}
 \end{note}
 
@@ -4159,8 +4161,9 @@
   void draw();                  // a definition is required somewhere
 };
 \end{codeblock}
-would make class \tcode{circle} non-abstract and a definition of
-\tcode{circle::draw()} must be provided.
+would make class \tcode{circle} non-abstract;
+the program is ill-formed, no diagnostic required,
+unless a definition of \tcode{circle::draw()} is provided\iref{basic.def.odr}.
 \end{example}
 
 \pnum
@@ -4349,14 +4352,14 @@
 \tcode{A}.
 This implies, for example, that access checking on the first use of
 \tcode{A::I}
-must be deferred until it is determined that this use of
+is deferred until it is determined that this use of
 \tcode{A::I}
 is as the return type of a member of class
 \tcode{A}.
 Similarly, the use of \tcode{A::B} as a
 \grammarterm{base-specifier} is well-formed because \tcode{D}
 is derived from \tcode{A}, so checking of \grammarterm{base-specifier}{s}
-must be deferred until the entire \grammarterm{base-specifier-list} has been seen.
+is deferred until the entire \grammarterm{base-specifier-list} has been seen.
 \end{example}
 
 \pnum

source/compatibility.tex

@@ -2508,8 +2508,8 @@
 Semantic transformation.
 In \Cpp{}, the initializer for one of a set of
 mutually-referential file-local objects with static storage
-duration must invoke a function
-call to achieve the initialization.
+duration is expected to invoke a function
+to achieve the initialization.
 \howwide
 Seldom.
 
@@ -2708,7 +2708,7 @@
 \tcode{sizeof(char*)}
 in C.
 \difficulty
-Programs must add explicit casts to the appropriate rvalue.
+Programs are required to add explicit casts to the appropriate rvalue.
 \howwide
 Rare.
 
@@ -2744,7 +2744,7 @@
 return-value mechanisms for the return of class objects.
 If
 some flow paths execute a return without specifying any value,
-the implementation must embody many more complications.
+the implementation gets more complicated.
 Besides,
 promising to return a value of a given type, and then not returning
 such a value, has always been recognized to be a questionable
@@ -2803,7 +2803,7 @@
 
 \diffref{dcl.typedef}
 \change
-A \Cpp{} \grammarterm{typedef-name} must be different from any class type name declared
+A \Cpp{} \grammarterm{typedef-name} is required to be different from any class type name declared
 in the same scope (except if the typedef is a synonym of the class name with the
 same name). In C, a \grammarterm{typedef-name} and a struct tag name declared in the same scope
 can have the same name (because they have different name spaces).
@@ -2836,9 +2836,9 @@
 
 \diffref{dcl.type} [see also \ref{basic.link}]
 \change
-Const objects must be initialized in \Cpp{} but can be left uninitialized in C.
+Const objects are required to be initialized in \Cpp{} but can be left uninitialized in C.
 \rationale
-A const object cannot be assigned to so it must be initialized
+A const object cannot be assigned to so it is required to be initialized
 to hold a useful value.
 \effect
 Deletion of semantically well-defined feature.
@@ -2888,8 +2888,8 @@
 This feature was marked as ``obsolescent'' in C.
 \difficulty
 Syntactic transformation.
-The function declarations using C incomplete declaration style must
-be completed to become full prototype declarations.
+The function declarations using C incomplete declaration style
+need to be completed to become full prototype declarations.
 A program may need to be updated further if different calls to the
 same (non-prototype) function have different numbers of arguments or
 if the type of corresponding arguments differed.
@@ -2917,7 +2917,7 @@
 Deletion of semantically well-defined feature.
 \difficulty
 Semantic transformation.
-The type definitions must be moved to file scope, or in header files.
+The type definitions need to be moved to file scope, or in header files.
 \howwide
 Seldom.
 This style of type definition is seen as poor coding style.
@@ -2941,7 +2941,7 @@
 compared to the corresponding functionality in C\@.
 In \Cpp{},
 designators for non-static data members
-must be specified in declaration order,
+need to be specified in declaration order,
 designators for array elements and nested designators
 are not supported,
 and
@@ -2960,7 +2960,7 @@
 \rationale
 In \Cpp{}, members are destroyed in reverse construction order
 and the elements of an initializer list are evaluated in lexical order,
-so member initializers must be specified in order.
+so member initializers need to be specified in order.
 Array designators conflict with \grammarterm{lambda-expression} syntax.
 Nested designators are seldom used.
 \effect
@@ -2974,7 +2974,8 @@
 \diffref{dcl.init.string}
 \change
 In \Cpp{}, when initializing an array of character with a string, the number of
-characters in the string (including the terminating \tcode{'\textbackslash 0'}) must not exceed the
+characters in the string (including the terminating \tcode{'\textbackslash 0'})
+is required not to exceed the
 number of elements in the array. In C, an array can be initialized with a string even if
 the array is not large enough to contain the string-terminating \tcode{'\textbackslash 0'}.
 
@@ -2989,7 +2990,7 @@
 Deletion of semantically well-defined feature.
 \difficulty
 Semantic transformation.
-The arrays must be declared one element bigger to contain the
+The arrays need to be declared one element bigger to contain the
 string terminating \tcode{'\textbackslash 0'}.
 \howwide
 Seldom.
@@ -3141,7 +3142,7 @@
 \difficulty
 Semantic transformation.
 If volatile semantics are required for the copy,
-a user-declared constructor or assignment must
+a user-declared constructor or assignment needs to
 be provided.
 If non-volatile semantics are required,
 an explicit

source/containers.tex

@@ -594,8 +594,9 @@
 All other constructors for these container types take a
 \tcode{const allocator_type\&} argument.
 \begin{note}
-If an invocation of a constructor uses the default value of an optional
-allocator argument, then the allocator type must support value-initialization.
+Invocation of a constructor that uses the default value of an optional
+allocator argument is ill-formed
+unless the allocator type supports value-initialization.
 \end{note}
 A copy of this allocator is used for any memory allocation and element construction
 performed, by these constructors and by all member functions,

source/declarations.tex

@@ -332,7 +332,7 @@
 
 void g(char c) {
   f(0);             // OK
-  f(c);             // error on implementations where \tcode{sizeof(int) > 1}: must be \tcode{int}-sized
+  f(c);             // error on implementations where \tcode{sizeof(int) > 1}: \tcode{must be int-sized}
 }
 \end{codeblock}
 \end{example}
@@ -1196,10 +1196,11 @@
 \pnum
 \begin{note}
 Declaring a variable \keyword{const} can affect its linkage\iref{dcl.stc}
-and its usability in constant expressions\iref{expr.const}. As
-described in~\ref{dcl.init}, the definition of an object or subobject
-of const-qualified type must specify an initializer or be subject to
-default-initialization.
+and its usability in constant expressions\iref{expr.const}.
+As described in~\ref{dcl.init},
+the definition of an object or subobject of const-qualified type is ill-formed
+unless the definition specifies an initializer or
+be subject to default-initialization.
 \end{note}
 
 \pnum
@@ -3595,10 +3596,9 @@
 printf("a=%d b=%d", a, b);
 \end{codeblock}
 
-However, the first argument must be of a type
-that can be converted to a
-\keyword{const}
-\tcode{char*}.
+However, the program is ill-formed
+unless the first argument is of a type
+that can be converted to a \keyword{const} \tcode{char*}.
 \end{example}
 \begin{note}
 The standard header \libheaderref{cstdarg}
@@ -4963,7 +4963,7 @@
 are the first $n$ elements of the aggregate,
 where $n$ is the number of elements in the initializer list.
 \item
-Otherwise, the initializer list must be \tcode{\{\}},
+Otherwise, the initializer list is \tcode{\{\}},
 and there are no explicitly initialized elements.
 \end{itemize}