[Ada] Incorrect error on inline protected function

This patch fixes a bug where if a protected function has a pragma
Inline, and has no local variables, and the body consists of a single
extended_return_statement, and the result type is an indefinite
composite subtype, and inlining is enabled, the compiler gives an error,
even though the program is legal.

2019-08-14  Bob Duff  <duff@adacore.com>

gcc/ada/

	* inline.adb (Check_And_Split_Unconstrained_Function): Ignore
	protected functions to get rid of spurious error. The
	transformation done by this procedure triggers legality errors
	in the generated code in this case.

gcc/testsuite/

	* gnat.dg/inline19.adb, gnat.dg/inline19.ads: New testcase.

From-SVN: r274467

5 files changed, 50 insertions, 0 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 4e7daba..4063f93 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,5 +1,12 @@
 2019-08-14  Bob Duff  <duff@adacore.com>
 
+	* inline.adb (Check_And_Split_Unconstrained_Function): Ignore
+	protected functions to get rid of spurious error. The
+	transformation done by this procedure triggers legality errors
+	in the generated code in this case.
+
+2019-08-14  Bob Duff  <duff@adacore.com>
+
 	* sem_prag.adb (Process_Compile_Time_Warning_Or_Error): Defer
 	processing to the back end in all cases where the pragma's
 	condition is not known at compile time during the front end
diff --git a/gcc/ada/inline.adb b/gcc/ada/inline.adb
index 05830e1..5dbd9a1 100644
--- a/gcc/ada/inline.adb
+++ b/gcc/ada/inline.adb
@@ -2041,6 +2041,8 @@ package body Inline is
          Original_Body   : Node_Id;
          Body_To_Analyze : Node_Id;
 
+      --  Start of processing for Build_Body_To_Inline
+
       begin
          pragma Assert (Current_Scope = Spec_Id);
 
@@ -2448,6 +2450,18 @@ package body Inline is
       elsif Present (Body_To_Inline (Decl)) then
          return;
 
+      --  Do not generate a body to inline for protected functions, because the
+      --  transformation generates a call to a protected procedure, causing
+      --  spurious errors. We don't inline protected operations anyway, so
+      --  this is no loss. We might as well ignore intrinsics and foreign
+      --  conventions as well -- just allow Ada conventions.
+
+      elsif not (Convention (Spec_Id) = Convention_Ada
+        or else Convention (Spec_Id) = Convention_Ada_Pass_By_Copy
+        or else Convention (Spec_Id) = Convention_Ada_Pass_By_Reference)
+      then
+         return;
+
       --  Check excluded declarations
 
       elsif Present (Declarations (N))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cff4e5e..8575052 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2019-08-14  Bob Duff  <duff@adacore.com>
+
+	* gnat.dg/inline19.adb, gnat.dg/inline19.ads: New testcase.
+
 2019-08-14  Gary Dismukes  <dismukes@adacore.com>
 
 	* gnat.dg/equal11.adb, gnat.dg/equal11_interface.ads,
diff --git a/gcc/testsuite/gnat.dg/inline19.adb b/gcc/testsuite/gnat.dg/inline19.adb
new file mode 100644
index 0000000..01be738
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/inline19.adb
@@ -0,0 +1,17 @@
+--  { dg-do compile }
+--  { dg-options "-O2" }
+
+package body Inline19 is
+
+   S : String := "Hello";
+
+   protected body P is
+      function F return String is
+      begin
+         return Result : constant String := S do
+            null;
+         end return;
+      end F;
+   end P;
+
+end Inline19;
diff --git a/gcc/testsuite/gnat.dg/inline19.ads b/gcc/testsuite/gnat.dg/inline19.ads
new file mode 100644
index 0000000..7a2d35c
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/inline19.ads
@@ -0,0 +1,8 @@
+package Inline19 is
+
+   protected P is
+      function F return String;
+      pragma Inline (F);
+   end P;
+
+end Inline19;