The -gnatwc switch enables warnings for test condition outcomes that are
known at compile time. Such warnings are unlikely to be useful in the
case of an assertion expression (or a subexpression thereof), so do not
generate them in that case.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_warn.adb (Warn_On_Constant_Valid_Condition): Do not
generate a warning if the expression in question is an assertion
expression, or a subexpression thereof. But do call
Test_Comparison so that it can generate warnings for the cases
that it generates warnings for.
* sem_prag.ads: Modify Assertion_Expression_Pragma constant so
that the predicate Sem_Util.In_Assertion_Expression_Pragma
returns True for the expression of a Compile_Time_Error pragma.diff --git a/gcc/ada/sem_prag.ads b/gcc/ada/sem_prag.ads
--- a/gcc/ada/sem_prag.ads
+++ b/gcc/ada/sem_prag.ads
@@ -135,6 +135,7 @@ package Sem_Prag is
Pragma_Assert_And_Cut => True,
Pragma_Assume => True,
Pragma_Check => True,
+ Pragma_Compile_Time_Error => True,
Pragma_Contract_Cases => True,
Pragma_Default_Initial_Condition => True,
Pragma_Initial_Condition => True,
diff --git a/gcc/ada/sem_warn.adb b/gcc/ada/sem_warn.adb
--- a/gcc/ada/sem_warn.adb
+++ b/gcc/ada/sem_warn.adb
@@ -3401,9 +3401,14 @@ package body Sem_Warn is
False_Result => False_Result);
-- Warn on a possible evaluation to False / True in the presence of
- -- invalid values.
+ -- invalid values. But issue no warning for an assertion expression
+ -- (or a subexpression thereof); in particular, we don't want a
+ -- warning about an assertion that will always succeed.
- if True_Result then
+ if In_Assertion_Expression_Pragma (Op) then
+ null;
+
+ elsif True_Result then
Error_Msg_N
("condition can only be False if invalid values present?c?", Op);
