[COMMITTED] ada: Fix internal error on declare expression in expression function

Message ID 20231128093851.2970777-1-poulhies@adacore.com
State Committed
Commit e95a42ec9a6be3edb6d8e31273ffcf64a40c0d3d
Headers
Series [COMMITTED] ada: Fix internal error on declare expression in expression function |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 warning Patch is already merged
linaro-tcwg-bot/tcwg_gcc_build--master-arm warning Patch is already merged

Commit Message

Marc Poulhiès Nov. 28, 2023, 9:38 a.m. UTC
  From: Eric Botcazou <ebotcazou@adacore.com>

When the expression function is not a completion, its (return) expression
does not cause freezing so analyzing the declare expression in this context
must not freeze the type of the object.

The change also contains another fix, which makes it so that the compiler
does not evaluate a nonstatic representation attribute of a scalar subtype
in the same context if the subtype is not already frozen.

gcc/ada/

	* sem_attr.adb (Eval_Attribute): Do not proceed in a spec expression
	for nonstatic representation attributes of a scalar subtype when the
	subtype is not frozen.
	* sem_ch3.adb (Analyze_Object_Declaration): Do not freeze the type
	of the object in a spec expression.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_attr.adb | 20 ++++++++++++++++++++
 gcc/ada/sem_ch3.adb  |  5 +++--
 2 files changed, 23 insertions(+), 2 deletions(-)
  

Patch

diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
index 000253e7993..a194360a601 100644
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -8693,6 +8693,26 @@  package body Sem_Attr is
             Set_Raises_Constraint_Error (N);
          end if;
 
+         --  RM 13.14(8/4): a nonstatic expression in a spec expression does
+         --  not cause freezing, so the representation attributes cannot be
+         --  evaluated at this point if the type is not already frozen.
+
+         if not Static
+           and then In_Spec_Expression
+           and then Id in Attribute_Alignment
+                       |  Attribute_Component_Size
+                       |  Attribute_Max_Alignment_For_Allocation
+                       |  Attribute_Max_Size_In_Storage_Elements
+                       |  Attribute_Object_Size
+                       |  Attribute_Size
+                       |  Attribute_Small
+                       |  Attribute_VADS_Size
+                       |  Attribute_Value_Size
+           and then not Is_Frozen (P_Type)
+         then
+            return;
+         end if;
+
       --  Array case. We enforce the constrained requirement of (RM 4.9(7-8))
       --  since we can't do anything with unconstrained arrays. In addition,
       --  only the First, Last and Length attributes are possibly static.
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index ca60850a2b3..aed7828752b 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -4453,7 +4453,8 @@  package body Sem_Ch3 is
 
       --  If not a deferred constant, then the object declaration freezes
       --  its type, unless the object is of an anonymous type and has delayed
-      --  aspects. In that case the type is frozen when the object itself is.
+      --  aspects (in that case the type is frozen when the object itself is)
+      --  or the context is a spec expression.
 
       else
          Check_Fully_Declared (T, N);
@@ -4463,7 +4464,7 @@  package body Sem_Ch3 is
            and then Is_Itype (T)
          then
             Set_Has_Delayed_Freeze (T);
-         else
+         elsif not In_Spec_Expression then
             Freeze_Before (N, T);
          end if;
       end if;