minor changes to undefined behavior notes

Author: WalterBright

spec/arrays.dd

@@ -48,11 +48,8 @@ assert(*p == 6);
         will be aborted.)
         ))
 
-        $(UNDEFINED_BEHAVIOR
-        $(OL
-        $(LI Dereferencing a pointer that is not $(I null) and does not point
+        $(UNDEFINED_BEHAVIOR dereferencing a pointer that is not $(I null) and does not point
         to a valid object of type $(I T).)
-        ))
 
         $(P To set a pointer to point at an existing object, use the
         `&` *address of* operator:)

spec/const3.dd

@@ -322,10 +322,10 @@ int* q = cast(int*)p;
         the compiler will no longer be able to statically do so.
         )
 
-        $(P
-        Note that casting away a const qualifier and then mutating is undefined
-        behavior, too, even when the referenced data is mutable. This is so that
-        compilers and programmers can make assumptions based on const alone. For
+        $(UNDEFINED_BEHAVIOR
+        casting away a `const` qualifier and then mutating it,
+        even when the referenced data is mutable. This is so that
+        compilers and programmers can make assumptions based on `const` alone. For
         example, here it may be assumed that $(D f) does not alter $(D x):
         )
 

spec/declaration.dd

@@ -590,8 +590,9 @@ $(GNAME VoidInitializer):
         $(P Normally, variables are initialized either with an explicit
         $(GLINK Initializer) or are set to the default value for the
         type of the variable. If the $(I Initializer) is $(D void),
-        however, the variable is not initialized. If its value is
-        used before it is set, undefined program behavior will result.
+        however, the variable is not initialized.
+        Void initializers for objects that contain indirections is not
+        allowed in @safe code.
         )
 
         $(IMPLEMENTATION_DEFINED If a void initialized variable's value is

spec/function.dd

@@ -456,7 +456,7 @@ $(H3 $(LNAME2 pure-special-cases, Special Cases))
 
         $(UNDEFINED_BEHAVIOR occurs if these flags are not restored to their
         initial state upon function exit. It is the programmer's responsibility
-        to ensure this.)
+        to ensure this. Setting these flags is not allowed in `@safe` code.)
 
         $(P A pure function can perform impure operations in statements that are in a
         $(GLINK2 version, ConditionalStatement)
@@ -2969,6 +2969,10 @@ void test()
         is not allowed in @safe functions.
         )
 
+        $(UNDEFINED_BEHAVIOR Calling a function pointer that was set to point to
+        a function that requires a context pointer.
+        )
+
         ---
         struct S
         {

spec/lex.dd

@@ -403,8 +403,7 @@ $(GNAME TokenStringToken):
 
         $(P String literals are read only.)
 
-        $(UNDEFINED_BEHAVIOR Writes to string literals
-        cannot always be detected, but cause undefined behavior.)
+        $(UNDEFINED_BEHAVIOR writing to a string literal. This is not allowed in `@safe` code.)
 
 $(H3 $(LNAME2 wysiwyg, Wysiwyg Strings))
 

spec/statement.dd

@@ -1322,8 +1322,7 @@ $(H3 $(LNAME2 no-implicit-fallthrough, No Implicit Fall-Through))
         $(P A $(GLINK ScopeStatementList) must either be empty, or be ended with
         a $(GLINK ContinueStatement), $(GLINK BreakStatement),
         $(GLINK ReturnStatement), $(GLINK GotoStatement), $(GLINK2 expression, ThrowExpression)
-        or `assert(0)` expression unless this is the last case. This is to
-        set apart with C's error-prone implicit fall-through behavior.)
+        or `assert(0)` expression unless this is the last case.)
 
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