diff mbox series

[Ada] Spurious warning on useless assignment with target name

Message ID 20210505082005.GA31338@adacore.com
State New
Headers show
Series [Ada] Spurious warning on useless assignment with target name | expand

Commit Message

Pierre-Marie de Rodat May 5, 2021, 8:20 a.m. UTC 
An assignment to an entity E triggers an improper warning that an
immediately preceding assignment to E is useless, when the right-hand
side of the new assignment includes a target name, that is to say the
Ada2020 use of "@" to designate the left-hand side of the assignment.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_ch5.adb (Analyze_Assignment): Do not emit the warning that
	a previous value of the target object is useless if the
	right-hand side of the assignment includes target names.
diff mbox series

Patch

diff --git a/gcc/ada/sem_ch5.adb b/gcc/ada/sem_ch5.adb
--- a/gcc/ada/sem_ch5.adb
+++ b/gcc/ada/sem_ch5.adb
@@ -1108,6 +1108,12 @@  package body Sem_Ch5 is
                --  warnings when an assignment is rewritten as another
                --  assignment, and gets tied up with itself.
 
+               --  We also omit the warning if the RHS includes target names,
+               --  that is to say the Ada2020 "@" that denotes an instance of
+               --  the LHS, which indicates that the current value is being
+               --  used. Note that this implicit reference to the entity on
+               --  the RHS is not treated as a source reference.
+
                --  There may have been a previous reference to a component of
                --  the variable, which in general removes the Last_Assignment
                --  field of the variable to indicate a relevant use of the
@@ -1126,6 +1132,7 @@  package body Sem_Ch5 is
                  and then Comes_From_Source (N)
                  and then In_Extended_Main_Source_Unit (Ent)
                  and then not Has_Deferred_Reference (Ent)
+                 and then not Has_Target_Names (N)
                then
                   Warn_On_Useless_Assignment (Ent, N);
                end if;