From 0af66bdce078d022e19dae1c83dfa06f7f622648 Mon Sep 17 00:00:00 2001 From: Ed Schonberg Date: Mon, 22 Jul 2019 13:56:31 +0000 Subject: [PATCH] [Ada] Spurious warning about a useless assignment This patch removes a spurious warning about a useless assignment, when a composite object is the target of an assignment and is an actual for an out parameter in a subsewuent call, and there is an intervening use of the object as the prefix of a selected component in an intervening operation. 2019-07-22 Ed Schonberg gcc/ada/ * sem_res.adb (Resolve_Selected_Component): If the prefix has a deferred reference, generate the correct reference now, to indicate that the previous assignment is used. This prevents spurious warnings on useless assignments when compiling with all warnings enabled. when there is a subsequent call in the same stqtement list, in which the prefix of the selected component is the actual for an out parameter. gcc/testsuite/ * gnat.dg/warn22.adb: New testcase. From-SVN: r273669 --- gcc/ada/ChangeLog | 10 ++++++++++ gcc/ada/sem_res.adb | 17 ++++++++++++++++ gcc/testsuite/ChangeLog | 4 ++++ gcc/testsuite/gnat.dg/warn22.adb | 34 ++++++++++++++++++++++++++++++++ 4 files changed, 65 insertions(+) create mode 100644 gcc/testsuite/gnat.dg/warn22.adb diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog index 38cc4b833a0..c42164b0042 100644 --- a/gcc/ada/ChangeLog +++ b/gcc/ada/ChangeLog @@ -1,3 +1,13 @@ +2019-07-22 Ed Schonberg + + * sem_res.adb (Resolve_Selected_Component): If the prefix has a + deferred reference, generate the correct reference now, to + indicate that the previous assignment is used. This prevents + spurious warnings on useless assignments when compiling with all + warnings enabled. when there is a subsequent call in the same + stqtement list, in which the prefix of the selected component is + the actual for an out parameter. + 2019-07-22 Eric Botcazou * exp_attr.adb (Expand_Loop_Entry_Attribute): Copy the condition diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb index 4ca74f8543c..fd4fedc3032 100644 --- a/gcc/ada/sem_res.adb +++ b/gcc/ada/sem_res.adb @@ -10625,8 +10625,25 @@ package body Sem_Res is if Is_Access_Type (Etype (P)) then T := Designated_Type (Etype (P)); Check_Fully_Declared_Prefix (T, P); + else T := Etype (P); + + -- If the prefix is an entity it may have a deferred reference set + -- during analysis of the selected component. After resolution we + -- can transform it into a proper reference. This prevents spurious + -- warnings on useless assignments when the same selected component + -- is the actual for an out parameter in a subsequent call. + + if Is_Entity_Name (P) + and then Has_Deferred_Reference (Entity (P)) + then + if May_Be_Lvalue (N) then + Generate_Reference (Entity (P), P, 'm'); + else + Generate_Reference (Entity (P), P, 'r'); + end if; + end if; end if; -- Set flag for expander if discriminant check required on a component diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index e9c2b5e3b7d..f8372bae481 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2019-07-22 Ed Schonberg + + * gnat.dg/warn22.adb: New testcase. + 2019-07-22 Eric Botcazou * gnat.dg/loop_invariant1.adb, gnat.dg/loop_invariant1.ads: New diff --git a/gcc/testsuite/gnat.dg/warn22.adb b/gcc/testsuite/gnat.dg/warn22.adb new file mode 100644 index 00000000000..0a1692f6f49 --- /dev/null +++ b/gcc/testsuite/gnat.dg/warn22.adb @@ -0,0 +1,34 @@ +-- { dg-do compile } +-- { dg-options "-gnatwa" } + +with Ada.Text_IO; + +procedure Warn22 +is + type X is + record + Str : String (1 .. 3); + end record; + + type T is + record + Value : X; + end record; + + procedure Consume_Data (Item : out T) is + begin + Item := (Value => (Str => "Bar")); + end Consume_Data; + + Baz : T; +begin + + Baz := (Value => (Str => "Foo")); + + Ada.Text_IO.Put_Line (Baz.Value.Str); + + Consume_Data (Baz); + + Ada.Text_IO.Put_Line (Baz.Value.Str); + +end Warn22; -- 2.30.2