From bea1e14490e4abc4b67bae8fdca5196bb93acd2d Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Thu, 22 Jun 2023 22:07:41 +0200
Subject: [PATCH] Fortran: ABI for scalar CHARACTER(LEN=1),VALUE dummy argument
 [PR110360]

gcc/fortran/ChangeLog:

	PR fortran/110360
	* trans-expr.cc (gfc_conv_procedure_call): Pass actual argument
	to scalar CHARACTER(1),VALUE dummy argument by value.

gcc/testsuite/ChangeLog:

	PR fortran/110360
	* gfortran.dg/value_9.f90: New test.
---
 gcc/fortran/trans-expr.cc             | 19 +++++++
 gcc/testsuite/gfortran.dg/value_9.f90 | 78 +++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 gcc/testsuite/gfortran.dg/value_9.f90

diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 3c209bcde97..c92fccd0be2 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -6392,6 +6392,25 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 		  else
 		    {
 		    gfc_conv_expr (&parmse, e);
+
+		    /* ABI: actual arguments to CHARACTER(len=1),VALUE
+		       dummy arguments are actually passed by value.
+		       The BIND(C) case is handled elsewhere.
+		       TODO: truncate constant strings to length 1.  */
+		    if (fsym->ts.type == BT_CHARACTER
+			&& !fsym->ts.is_c_interop
+			&& fsym->ts.u.cl->length->expr_type == EXPR_CONSTANT
+			&& fsym->ts.u.cl->length->ts.type == BT_INTEGER
+			&& (mpz_cmp_ui
+			    (fsym->ts.u.cl->length->value.integer, 1) == 0)
+			&& e->expr_type != EXPR_CONSTANT)
+		      {
+			parmse.expr = gfc_string_to_single_character
+			  (build_int_cst (gfc_charlen_type_node, 1),
+			   parmse.expr,
+			   e->ts.kind);
+		      }
+
 		    if (fsym->attr.optional
 			&& fsym->ts.type != BT_CLASS
 			&& fsym->ts.type != BT_DERIVED)
diff --git a/gcc/testsuite/gfortran.dg/value_9.f90 b/gcc/testsuite/gfortran.dg/value_9.f90
new file mode 100644
index 00000000000..f6490645e27
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/value_9.f90
@@ -0,0 +1,78 @@
+! { dg-do run }
+! PR fortran/110360 - ABI for scalar character(len=1),value dummy argument
+
+program p
+  implicit none
+  character,               allocatable :: ca
+  character,               pointer     :: cp
+  character(len=:),        allocatable :: cd
+  character      (kind=4), allocatable :: ca4
+  character      (kind=4), pointer     :: cp4
+  character(len=:,kind=4), allocatable :: cd4
+  integer :: a = 65
+  allocate (ca, cp, ca4, cp4)
+
+  ! Check len=1 actual argument cases first
+  ca  =   "a"; cp  =   "b"; cd  =   "c"
+  ca4 = 4_"d"; cp4 = 4_"e"; cd4 = 4_"f"
+  call val  ("B","B")
+  call val  ("A",char(65))
+  call val  ("A",char(a))
+  call val  ("A",mychar(65))
+  call val  ("A",mychar(a))
+  call val4 (4_"C",4_"C")
+  call val4 (4_"A",char(65,kind=4))
+  call val4 (4_"A",char(a, kind=4))
+  call val  (ca,ca)
+  call val  (cp,cp)
+  call val  (cd,cd)
+  call val4 (ca4,ca4)
+  call val4 (cp4,cp4)
+  call val4 (cd4,cd4)
+  call sub  ("S")
+  call sub4 (4_"T")
+
+  ! Check that always the first character of the string is finally used
+  call val  (  "U++",  "U--")
+  call val4 (4_"V**",4_"V//")
+  call sub  (  "WTY")
+  call sub4 (4_"ZXV")
+  cd = "gkl"; cd4 = 4_"hmn"
+  call val  (cd,cd)
+  call val4 (cd4,cd4)
+  call sub  (cd)
+  call sub4 (cd4)
+  deallocate (ca, cp, ca4, cp4, cd, cd4)
+contains
+  subroutine val (x, c)
+    character(kind=1), intent(in) :: x  ! control: pass by reference
+    character(kind=1), value      :: c
+    print *, "by value(kind=1): ", c
+    if (c /= x)   stop 1
+    c = "*"
+    if (c /= "*") stop 2
+  end
+
+  subroutine val4 (x, c)
+    character(kind=4), intent(in) :: x  ! control: pass by reference
+    character(kind=4), value      :: c
+    print *, "by value(kind=4): ", c
+    if (c /= x)     stop 3
+    c = 4_"#"
+    if (c /= 4_"#") stop 4
+  end
+
+  subroutine sub (s)
+    character(*), intent(in) :: s
+    call val (s, s)
+  end
+  subroutine sub4 (s)
+    character(kind=4,len=*), intent(in) :: s
+    call val4 (s, s)
+  end
+
+  character function mychar (i)
+    integer, intent(in) :: i
+    mychar = char (i)
+  end
+end
--
2.35.3