[Ada] tech debt: Clean up Uint fields, such as Esize

gcc/ada/

	* atree.ads: Comment improvements. How is a "completely new
	node" different from a "new node"? Document default values
	corresponding to field types.
	* exp_ch7.adb (Process_Tagged_Type_Declaration): Use
	higher-level Scope_Depth instead of Scope_Depth_Value.  Remove
	confusing comment: not clear what a "true" library level package
	is.
	* uintp.adb (Image_Out): Print No_Uint in a more readable way.
	* gen_il-gen.adb, gen_il-gen-gen_entities.adb,
	gen_il-gen-gen_nodes.adb, gen_il-types.ads: Tighten up the
	subtypes of fields whose type is Uint, where possible; use
	more-constrained subtypes such as Unat.
	* einfo-utils.adb, einfo-utils.ads, exp_attr.adb,
	exp_ch3.adb, exp_intr.adb, exp_unst.adb, exp_util.adb,
	freeze.adb, repinfo.adb, sem.adb, sem_ch12.adb, sem_ch13.adb,
	sem_ch3.adb, sem_ch8.adb, sem_util.adb, sprint.adb, treepr.adb:
	No longer use Uint_0 to indicate "unknown" or "not yet known"
	for various fields whose type is Uint. Use No_Uint for that,
	except in a small number of legacy cases that cause test
	failures. Protect many queries of such fields with calls to
	Known_... functions. Improve comments.
	* exp_aggr.adb: Likewise.
	(Is_OK_Aggregate): Check whether Csiz is present.
	(Aggr_Assignment_OK_For_Backend): Ensure we do not access an
	uninitialized size.
	* exp_strm.adb (Build_Elementary_Input_Call,
	Build_Elementary_Write_Call): Check whether P_Size is present.
	* cstand.adb: Leave Component_Size of Any_Composite unknown.
	Similar for RM_Size of Standard_Exception_Type.  These should
	not be used.
	* einfo.ads: Comment improvements.
	* exp_disp.ads: Minor.
	* gen_il-internals.ads, gen_il-internals.adb: Minor.
	* sinfo-utils.adb: Take advantage of full-coverage rules.
	* types.h: Minor.

1 files changed, 26 insertions, 19 deletions

diff --git a/gcc/ada/atree.ads b/gcc/ada/atree.ads
index 2f3ca40..4861236 100644
--- a/gcc/ada/atree.ads
+++ b/gcc/ada/atree.ads
@@ -230,11 +230,18 @@ package Atree is
    function New_Node
      (New_Node_Kind : Node_Kind;
       New_Sloc      : Source_Ptr) return Node_Id;
-   --  Allocates a completely new node with the given node type and source
-   --  location values. All other fields are set to their standard defaults:
+   --  Allocates a new node with the given node type and source location
+   --  values. Fields have defaults depending on their type:
+
+   --    Flag: False
+   --    Node_Id: Empty
+   --    List_Id: Empty
+   --    Elist_Id: No_Elist
+   --    Uint: No_Uint
    --
-   --    Empty for all FieldN fields
-   --    False for all FlagN fields
+   --    Name_Id, String_Id, Valid_Uint, Unat, Upos, Nonzero_Uint, Ureal:
+   --      No default. This means it is an error to call the getter before
+   --      calling the setter.
    --
    --  The usual approach is to build a new node using this function and
    --  then, using the value returned, use the Set_xxx functions to set
@@ -288,16 +295,16 @@ package Atree is
    --  with copying aspect specifications where this is required.
 
    function New_Copy (Source : Node_Id) return Node_Id;
-   --  This function allocates a completely new node, and then initializes
-   --  it by copying the contents of the source node into it. The contents of
-   --  the source node is not affected. The target node is always marked as
-   --  not being in a list (even if the source is a list member), and not
-   --  overloaded. The new node will have an extension if the source has
-   --  an extension. New_Copy (Empty) returns Empty, and New_Copy (Error)
-   --  returns Error. Note that, unlike Copy_Separate_Tree, New_Copy does not
-   --  recursively copy any descendants, so in general parent pointers are not
-   --  set correctly for the descendants of the copied node. Both normal and
-   --  extended nodes (entities) may be copied using New_Copy.
+   --  This function allocates a new node, and then initializes it by copying
+   --  the contents of the source node into it. The contents of the source node
+   --  is not affected. The target node is always marked as not being in a list
+   --  (even if the source is a list member), and not overloaded. The new node
+   --  will have an extension if the source has an extension. New_Copy (Empty)
+   --  returns Empty, and New_Copy (Error) returns Error. Note that, unlike
+   --  Copy_Separate_Tree, New_Copy does not recursively copy any descendants,
+   --  so in general parent pointers are not set correctly for the descendants
+   --  of the copied node. Both normal and extended nodes (entities) may be
+   --  copied using New_Copy.
 
    function Relocate_Node (Source : Node_Id) return Node_Id;
    --  Source is a non-entity node that is to be relocated. A new node is
@@ -340,11 +347,11 @@ package Atree is
    --  Exchange the contents of two entities. The parent pointers are switched
    --  as well as the Defining_Identifier fields in the parents, so that the
    --  entities point correctly to their original parents. The effect is thus
-   --  to leave the tree completely unchanged in structure, except that the
-   --  entity ID values of the two entities are interchanged. Neither of the
-   --  two entities may be list members. Note that entities appear on two
-   --  semantic chains: Homonym and Next_Entity: the corresponding links must
-   --  be adjusted by the caller, according to context.
+   --  to leave the tree unchanged in structure, except that the entity ID
+   --  values of the two entities are interchanged. Neither of the two entities
+   --  may be list members. Note that entities appear on two semantic chains:
+   --  Homonym and Next_Entity: the corresponding links must be adjusted by the
+   --  caller, according to context.
 
    procedure Extend_Node (Source : Node_Id);
    --  This turns a node into an entity; it function is used only by Sinfo.CN.