2014-02-25 Robert Dewar <dewar@adacore.com>

	* exp_ch7.adb, sem_util.adb, sem_util.ads, exp_ch6.adb: Minor
	reformatting.

2014-02-25  Ed Schonberg  <schonberg@adacore.com>

	* freeze.adb (Freeze_Entity): If the return type of a function
	is a limited view, and the non-limited view has not been seen yet,
	defer freezing to some later point.

2014-02-25  Robert Dewar  <dewar@adacore.com>

	* sem_ch3.adb: Minor reformatting.

2014-02-25  Robert Dewar  <dewar@adacore.com>

	* s-excdeb.ads, s-except.ads, s-exctab.adb, s-exctab.ads, s-finmas.ads,
	s-htable.adb, s-htable.ads, s-imenne.adb, s-imenne.ads, s-imgenu.adb,
	s-imgenu.ads, s-mastop.adb, s-mastop.ads, s-memory-vms_64.adb,
	s-memory-vms_64.ads, s-memory.adb, s-memory.ads, s-os_lib.adb,
	s-os_lib.ads, s-parame.adb, s-parame.ads, s-purexc.ads, s-restri.adb,
	s-restri.ads, s-rident.ads, s-secsta.adb, s-secsta.ads, s-soflin.adb,
	s-soflin.ads, s-sopco3.adb, s-sopco3.ads, s-sopco4.adb, s-sopco4.ads,
	s-sopco5.adb, s-sopco5.ads, s-spsufi.ads, s-stache.adb, s-stache.ads,
	s-stalib.adb, s-stalib.ads, s-stoele.adb, s-stoele.ads, s-strcom.adb,
	s-strcom.ads, s-strhas.adb, s-string.adb, s-string.ads, s-strops.adb,
	s-strops.ads, s-ststop.adb, s-ststop.ads, s-traceb.adb, s-traceb.ads,
	s-traent.adb, s-traent.ads, s-unstyp.ads, s-utf_32.adb, s-utf_32.ads,
	s-wchcnv.adb, s-wchcnv.ads, s-wchcon.adb, s-wchcon.ads, s-wchjis.adb,
	s-wchjis.ads, sem_ch11.adb, sem_ch4.adb, sem_ch5.adb, sem_prag.adb,
	snames.ads-tmpl: Change Compiler_Unit everywhere to
	Compiler_Unit_Warning.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@208135 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 37 insertions, 4 deletions

diff --git a/gcc/ada/sem_prag.adb b/gcc/ada/sem_prag.adb
index a5eaf1304bd..a1d381c8b90 100644
--- a/gcc/ada/sem_prag.adb
+++ b/gcc/ada/sem_prag.adb
@@ -2827,6 +2827,10 @@ package body Sem_Prag is
    -- Analyze_Pragma --
    --------------------
 
+   --------------------
+   -- Analyze_Pragma --
+   --------------------
+
    procedure Analyze_Pragma (N : Node_Id) is
       Loc     : constant Source_Ptr := Sloc (N);
       Prag_Id : Pragma_Id;
@@ -12240,11 +12244,39 @@ package body Sem_Prag is
             GNAT_Pragma;
             Process_Compile_Time_Warning_Or_Error;
 
-         -------------------
-         -- Compiler_Unit --
-         -------------------
+         ---------------------------
+         -- Compiler_Unit_Warning --
+         ---------------------------
+
+         --  pragma Compiler_Unit_Warning;
+
+         --  Historical note
+
+         --  Originally, we had only pragma Compiler_Unit, and it resulted in
+         --  errors not warnings. This means that we had introduced a big extra
+         --  inertia to compiler changes, since even if we implemented a new
+         --  feature, and even if all versions to be used for bootstrapping
+         --  implemented this new feature, we could not use it, since old
+         --  compilers would give errors for using this feature in units
+         --  having Compiler_Unit pragmas.
+
+         --  By changing Compiler_Unit to Compiler_Unit_Warning, we solve the
+         --  problem. We no longer have any units mentioning Compiler_Unit,
+         --  so old compilers see Compiler_Unit_Warning which is unrecognized,
+         --  and thus generates a warning which can be ignored. So that deals
+         --  with the problem of old compilers not implementing the newer form
+         --  of the pragma.
+
+         --  Newer compilers recognize the new pragma, but generate warning
+         --  messages instead of errors, which again can be ignored in the
+         --  case of an old compiler which implements a wanted new feature
+         --  but at the time felt like warning about it for older compilers.
+
+         --  We retain Compiler_Unit so that new compilers can be used to build
+         --  older run-times that use this pragma. That's an unusual case, but
+         --  it's easy enough to handle, so why not?
 
-         when Pragma_Compiler_Unit =>
+         when Pragma_Compiler_Unit | Pragma_Compiler_Unit_Warning =>
             GNAT_Pragma;
             Check_Arg_Count (0);
             Set_Is_Compiler_Unit (Get_Source_Unit (N));
@@ -25521,6 +25553,7 @@ package body Sem_Prag is
       Pragma_Compile_Time_Error             => -1,
       Pragma_Compile_Time_Warning           => -1,
       Pragma_Compiler_Unit                  =>  0,
+      Pragma_Compiler_Unit_Warning          =>  0,
       Pragma_Complete_Representation        =>  0,
       Pragma_Complex_Representation         =>  0,
       Pragma_Component_Alignment            => -1,