In Ada 2012 a qualified expression is a valid name, and for example a function
call that is disambiguated by means of a qualification can appear in the place
of a constant object. On the other hand A qualified expression that appears as
a statement denotes a machine code insertion. With the new rule, a qualified
expression by itself is parsed as a parameterless procedure call, and must be
rewritten and analyzed as a code statement.
The following must compile quietly:
gcc -c -gnat12 -gnatws code_statement.adb
---
WITH MACHINE_CODE; -- N/A => ERROR.
USE MACHINE_CODE;
PROCEDURE code_statement IS
PROCEDURE CODE IS
BEGIN
Asm_Insn'(Asm ("nop"));
END;
BEGIN
CODE;
END code_statement;
Tested on x86_64-pc-linux-gnu, committed on trunk
2011-10-13 Ed Schonberg <[email protected]>
* sem_ch6.adb (Analyze_Procedure_Call_Statement): In Ada 2012 mode,
if the prefix of the call is a qualified expression, rewrite as
a code statement.
* sem_ch13.adb (Analyze_Code_Statement): In Ada 2012 mode, the
code statement is legal if it is a rewriting of a procedure call.
Index: sem_ch6.adb
===================================================================
--- sem_ch6.adb (revision 179894)
+++ sem_ch6.adb (working copy)
@@ -1340,6 +1340,15 @@
Analyze (P);
Analyze_Call_And_Resolve;
+ -- In Ada 2012. a qualified expression is a name, but it cannot be a
+ -- procedure name, so the construct can only be a qualified expression.
+
+ elsif Nkind (P) = N_Qualified_Expression
+ and then Ada_Version >= Ada_2012
+ then
+ Rewrite (N, Make_Code_Statement (Loc, Expression => P));
+ Analyze (N);
+
-- Anything else is an error
else
Index: sem_ch13.adb
===================================================================
--- sem_ch13.adb (revision 179894)
+++ sem_ch13.adb (working copy)
@@ -3364,11 +3364,19 @@
-- No statements other than code statements, pragmas, and labels.
-- Again we allow certain internally generated statements.
+ -- In Ada 2012, qualified expressions are names, and the code
+ -- statement is initially parsed as a procedure call.
Stmt := First (Statements (HSS));
while Present (Stmt) loop
StmtO := Original_Node (Stmt);
- if Comes_From_Source (StmtO)
+
+ if Ada_Version >= Ada_2012
+ and then Nkind (StmtO) = N_Procedure_Call_Statement
+ then
+ null;
+
+ elsif Comes_From_Source (StmtO)
and then not Nkind_In (StmtO, N_Pragma,
N_Label,
N_Code_Statement)
