diff --git a/gcc/fortran/io.c b/gcc/fortran/io.c
index d93dcfa..f47565c 100644
--- a/gcc/fortran/io.c
+++ b/gcc/fortran/io.c
@@ -909,6 +909,13 @@ data_desc:
if (u != FMT_POSINT)
{
+ if (flag_dec)
+ {
+ /* Assume a default width based on the variable size. */
+ saved_token = u;
+ break;
+ }
+
format_locus.nextc += format_string_pos;
gfc_error ("Positive width required in format "
"specifier %s at %L", token_to_string (t),
@@ -1030,6 +1037,13 @@ data_desc:
goto fail;
if (t != FMT_ZERO && t != FMT_POSINT)
{
+ if (flag_dec)
+ {
+ /* Assume the default width is expected here and continue lexing. */
+ value = 0; /* It doesn't matter what we set the value to here. */
+ saved_token = t;
+ break;
+ }
error = nonneg_required;
goto syntax;
}
@@ -1099,8 +1113,17 @@ data_desc:
goto fail;
if (t != FMT_ZERO && t != FMT_POSINT)
{
- error = nonneg_required;
- goto syntax;
+ if (flag_dec)
+ {
+ /* Assume the default width is expected here and continue lexing. */
+ value = 0; /* It doesn't matter what we set the value to here. */
+ saved_token = t;
+ }
+ else
+ {
+ error = nonneg_required;
+ goto syntax;
+ }
}
else if (is_input && t == FMT_ZERO)
{
diff --git a/gcc/testsuite/gfortran.dg/fmt_f_default_field_width.f90 b/gcc/testsuite/gfortran.dg/fmt_f_default_field_width.f90
new file mode 100644
index 0000000..b087b8f
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/fmt_f_default_field_width.f90
@@ -0,0 +1,43 @@
+! { dg-do run }
+! { dg-options -fdec }
+!
+! Test case for the default field widths enabled by the -fdec-format-defaults flag.
+!
+! This feature is not part of any Fortran standard, but it is supported by the
+! Oracle Fortran compiler and others.
+!
+! libgfortran uses printf() internally to implement FORMAT. If you print float
+! values to a higher precision than the type can actually store, the results
+! are implementation dependent: some platforms print zeros, others print random
+! numbers. Don't depend on this behaviour in tests because they will not be
+! portable.
+
+ character(50) :: buffer
+
+ real*4 :: real_4
+ real*8 :: real_8
+ real*16 :: real_16
+ integer :: len
+
+ real_4 = 4.18
+ write(buffer, '(A, F, A)') ':',real_4,':'
+ print *,buffer
+ if (buffer.ne.": 4.1799998:") call abort
+
+ real_4 = 0.00000018
+ write(buffer, '(A, F, A)') ':',real_4,':'
+ print *,buffer
+ if (buffer.ne.": 0.0000002:") call abort
+
+ real_8 = 4.18
+ write(buffer, '(A, F, A)') ':',real_8,':'
+ print *,buffer
+ len = len_trim(buffer)
+ if (len /= 27) call abort
+
+ real_16 = 4.18
+ write(buffer, '(A, F, A)') ':',real_16,':'
+ print *,buffer
+ len = len_trim(buffer)
+ if (len /= 44) call abort
+end
diff --git a/gcc/testsuite/gfortran.dg/fmt_g_default_field_width.f90 b/gcc/testsuite/gfortran.dg/fmt_g_default_field_width.f90
new file mode 100644
index 0000000..3d3a476
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/fmt_g_default_field_width.f90
@@ -0,0 +1,48 @@
+! { dg-do run }
+! { dg-options -fdec }
+!
+! Test case for the default field widths enabled by the -fdec-format-defaults flag.
+!
+! This feature is not part of any Fortran standard, but it is supported by the
+! Oracle Fortran compiler and others.
+!
+! libgfortran uses printf() internally to implement FORMAT. If you print float
+! values to a higher precision than the type can actually store, the results
+! are implementation dependent: some platforms print zeros, others print random
+! numbers. Don't depend on this behaviour in tests because they will not be
+! portable.
+
+ character(50) :: buffer
+
+ real*4 :: real_4
+ real*8 :: real_8
+ real*16 :: real_16
+ integer :: len
+
+ real_4 = 4.18
+ write(buffer, '(A, G, A)') ':',real_4,':'
+ print *,buffer
+ if (buffer.ne.": 4.180000 :") call abort
+
+ real_4 = 0.00000018
+ write(buffer, '(A, G, A)') ':',real_4,':'
+ print *,buffer
+ if (buffer.ne.": 0.1800000E-06:") call abort
+
+ real_4 = 18000000.4
+ write(buffer, '(A, G, A)') ':',real_4,':'
+ print *,buffer
+ if (buffer.ne.": 0.1800000E+08:") call abort
+
+ real_8 = 4.18
+ write(buffer, '(A, G, A)') ':',real_8,':'
+ print *,buffer
+ len = len_trim(buffer)
+ if (len /= 27) call abort
+
+ real_16 = 4.18
+ write(buffer, '(A, G, A)') ':',real_16,':'
+ print *,buffer
+ len = len_trim(buffer)
+ if (len /= 44) call abort
+end
diff --git a/gcc/testsuite/gfortran.dg/fmt_i_default_field_width.f90 b/gcc/testsuite/gfortran.dg/fmt_i_default_field_width.f90
new file mode 100644
index 0000000..ac4e165
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/fmt_i_default_field_width.f90
@@ -0,0 +1,38 @@
+! { dg-do run }
+! { dg-options -fdec }
+!
+! Test case for the default field widths enabled by the -fdec-format-defaults flag.
+!
+! This feature is not part of any Fortran standard, but it is supported by the
+! Oracle Fortran compiler and others.
+
+ character(50) :: buffer
+ character(1) :: colon
+
+ integer*2 :: integer_2
+ integer*4 :: integer_4
+ integer*8 :: integer_8
+
+ write(buffer, '(A, I, A)') ':',12340,':'
+ print *,buffer
+ if (buffer.ne.": 12340:") call abort
+
+ read(buffer, '(A1, I, A1)') colon, integer_4, colon
+ if (integer_4.ne.12340) call abort
+
+ integer_2 = -99
+ write(buffer, '(A, I, A)') ':',integer_2,':'
+ print *,buffer
+ if (buffer.ne.": -99:") call abort
+
+ integer_8 = -11112222
+ write(buffer, '(A, I, A)') ':',integer_8,':'
+ print *,buffer
+ if (buffer.ne.": -11112222:") call abort
+
+! If the width is 7 and there are 7 leading zeroes, the result should be zero.
+ integer_2 = 789
+ buffer = '0000000789'
+ read(buffer, '(I)') integer_2
+ if (integer_2.ne.0) call abort
+end
diff --git a/libgfortran/io/format.c b/libgfortran/io/format.c
index c2abdd7..692b1ff 100644
--- a/libgfortran/io/format.c
+++ b/libgfortran/io/format.c
@@ -956,12 +956,33 @@ parse_format_list (st_parameter_dt *dtp, bool *seen_dd)
*seen_dd = true;
if (u != FMT_POSINT && u != FMT_ZERO)
{
+ if (dtp->common.flags & IOPARM_DT_DEC_EXT)
+ {
+ tail->u.real.w = DEFAULT_WIDTH;
+ tail->u.real.d = 0;
+ tail->u.real.e = -1;
+ fmt->saved_token = u;
+ break;
+ }
fmt->error = nonneg_required;
goto finished;
}
}
+ else if (u == FMT_ZERO)
+ {
+ fmt->error = posint_required;
+ goto finished;
+ }
else if (u != FMT_POSINT)
{
+ if (dtp->common.flags & IOPARM_DT_DEC_EXT)
+ {
+ tail->u.real.w = DEFAULT_WIDTH;
+ tail->u.real.d = 0;
+ tail->u.real.e = -1;
+ fmt->saved_token = u;
+ break;
+ }
fmt->error = posint_required;
goto finished;
}
@@ -1099,6 +1120,13 @@ parse_format_list (st_parameter_dt *dtp, bool *seen_dd)
{
if (t != FMT_POSINT)
{
+ if (dtp->common.flags & IOPARM_DT_DEC_EXT)
+ {
+ tail->u.integer.w = DEFAULT_WIDTH;
+ tail->u.integer.m = -1;
+ fmt->saved_token = t;
+ break;
+ }
fmt->error = posint_required;
goto finished;
}
@@ -1107,6 +1135,13 @@ parse_format_list (st_parameter_dt *dtp, bool *seen_dd)
{
if (t != FMT_ZERO && t != FMT_POSINT)
{
+ if (dtp->common.flags & IOPARM_DT_DEC_EXT)
+ {
+ tail->u.integer.w = DEFAULT_WIDTH;
+ tail->u.integer.m = -1;
+ fmt->saved_token = t;
+ break;
+ }
fmt->error = nonneg_required;
goto finished;
}
diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
index 5583183..d1d08e8 100644
--- a/libgfortran/io/io.h
+++ b/libgfortran/io/io.h
@@ -981,5 +981,55 @@ memset4 (gfc_char4_t *p, gfc_char4_t c, int k)
*p++ = c;
}
+/* Used in width fields to indicate that the default should be used */
+#define DEFAULT_WIDTH -1
+
+/* Defaults for certain format field descriptors. These are decided based on
+ * the type of the value being formatted.
+ *
+ * The behaviour here is modelled on the Oracle Fortran compiler. At the time
+ * of writing, the details were available at this URL:
+ *
+ * https://docs.oracle.com/cd/E19957-01/805-4939/6j4m0vnc3/index.html#z4000743746d
+ */
+
+static inline int
+default_width_for_integer (int kind)
+{
+ switch (kind)
+ {
+ case 1:
+ case 2: return 7;
+ case 4: return 12;
+ case 8: return 23;
+ case 16: return 44;
+ default: return 0;
+ }
+}
+
+static inline int
+default_width_for_float (int kind)
+{
+ switch (kind)
+ {
+ case 4: return 15;
+ case 8: return 25;
+ case 16: return 42;
+ default: return 0;
+ }
+}
+
+static inline int
+default_precision_for_float (int kind)
+{
+ switch (kind)
+ {
+ case 4: return 7;
+ case 8: return 16;
+ case 16: return 33;
+ default: return 0;
+ }
+}
+
#endif
diff --git a/libgfortran/io/read.c b/libgfortran/io/read.c
index 2c9de48..e911e35 100644
--- a/libgfortran/io/read.c
+++ b/libgfortran/io/read.c
@@ -629,6 +629,12 @@ read_decimal (st_parameter_dt *dtp, const fnode *f, char *dest, int length)
w = f->u.w;
+ /* This is a legacy extension, and the frontend will only allow such cases
+ * through when -fdec-format-defaults is passed.
+ */
+ if (w == DEFAULT_WIDTH)
+ w = default_width_for_integer (length);
+
p = read_block_form (dtp, &w);
if (p == NULL)
diff --git a/libgfortran/io/write.c b/libgfortran/io/write.c
index a7307a8..c8e52fb 100644
--- a/libgfortran/io/write.c
+++ b/libgfortran/io/write.c
@@ -684,9 +684,8 @@ write_l (st_parameter_dt *dtp, const fnode *f, char *source, int len)
p[wlen - 1] = (n) ? 'T' : 'F';
}
-
static void
-write_boz (st_parameter_dt *dtp, const fnode *f, const char *q, int n)
+write_boz (st_parameter_dt *dtp, const fnode *f, const char *q, int n, int len)
{
int w, m, digits, nzero, nblank;
char *p;
@@ -719,6 +718,9 @@ write_boz (st_parameter_dt *dtp, const fnode *f, const char *q, int n)
/* Select a width if none was specified. The idea here is to always
print something. */
+ if (w == DEFAULT_WIDTH)
+ w = default_width_for_integer (len);
+
if (w == 0)
w = ((digits < m) ? m : digits);
@@ -845,6 +847,8 @@ write_decimal (st_parameter_dt *dtp, const fnode *f, const char *source,
/* Select a width if none was specified. The idea here is to always
print something. */
+ if (w == DEFAULT_WIDTH)
+ w = default_width_for_integer (len);
if (w == 0)
w = ((digits < m) ? m : digits) + nsign;
@@ -1187,13 +1191,13 @@ write_b (st_parameter_dt *dtp, const fnode *f, const char *source, int len)
if (len > (int) sizeof (GFC_UINTEGER_LARGEST))
{
p = btoa_big (source, itoa_buf, len, &n);
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
else
{
n = extract_uint (source, len);
p = btoa (n, itoa_buf, sizeof (itoa_buf));
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
}
@@ -1208,13 +1212,13 @@ write_o (st_parameter_dt *dtp, const fnode *f, const char *source, int len)
if (len > (int) sizeof (GFC_UINTEGER_LARGEST))
{
p = otoa_big (source, itoa_buf, len, &n);
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
else
{
n = extract_uint (source, len);
p = otoa (n, itoa_buf, sizeof (itoa_buf));
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
}
@@ -1228,13 +1232,13 @@ write_z (st_parameter_dt *dtp, const fnode *f, const char *source, int len)
if (len > (int) sizeof (GFC_UINTEGER_LARGEST))
{
p = ztoa_big (source, itoa_buf, len, &n);
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
else
{
n = extract_uint (source, len);
p = gfc_xtoa (n, itoa_buf, sizeof (itoa_buf));
- write_boz (dtp, f, p, n);
+ write_boz (dtp, f, p, n, len);
}
}
@@ -1504,7 +1508,7 @@ size_from_kind (st_parameter_dt *dtp, const fnode *f, int kind)
{
int size;
- if (f->format == FMT_F && f->u.real.w == 0)
+ if ((f->format == FMT_F && f->u.real.w == 0) || f->u.real.w == DEFAULT_WIDTH)
{
switch (kind)
{
diff --git a/libgfortran/io/write_float.def b/libgfortran/io/write_float.def
index 7f0aa1d..73dc910 100644
--- a/libgfortran/io/write_float.def
+++ b/libgfortran/io/write_float.def
@@ -113,7 +113,8 @@ determine_precision (st_parameter_dt * d
static void
build_float_string (st_parameter_dt *dtp, const fnode *f, char *buffer,
size_t size, int nprinted, int precision, int sign_bit,
- bool zero_flag, int npad, char *result, size_t *len)
+ bool zero_flag, int npad, int default_width, char *result,
+ size_t *len)
{
char *put;
char *digits;
@@ -132,8 +133,17 @@ build_float_string (st_parameter_dt *dtp
sign_t sign;
ft = f->format;
- w = f->u.real.w;
- d = f->u.real.d;
+ if (f->u.real.w == DEFAULT_WIDTH)
+ /* This codepath can only be reached with -fdec-format-defaults. */
+ {
+ w = default_width;
+ d = precision;
+ }
+ else
+ {
+ w = f->u.real.w;
+ d = f->u.real.d;
+ }
p = dtp->u.p.scale_factor;
*len = 0;
@@ -959,6 +969,11 @@ determine_en_precision (st_parameter_dt
int save_scale_factor;\
volatile GFC_REAL_ ## x temp;\
save_scale_factor = dtp->u.p.scale_factor;\
+ if (w == DEFAULT_WIDTH)\
+ {\
+ w = default_width;\
+ d = precision;\
+ }\
switch (dtp->u.p.current_unit->round_status)\
{\
case ROUND_ZERO:\
@@ -1034,7 +1049,8 @@ determine_en_precision (st_parameter_dt
nprinted = FDTOA(y,precision,m);\
}\
build_float_string (dtp, &newf, buffer, size, nprinted, precision,\
- sign_bit, zero_flag, npad, result, res_len);\
+ sign_bit, zero_flag, npad, default_width,\
+ result, res_len);\
dtp->u.p.scale_factor = save_scale_factor;\
}\
else\
@@ -1044,7 +1060,8 @@ determine_en_precision (st_parameter_dt
else\
nprinted = DTOA(y,precision,m);\
build_float_string (dtp, f, buffer, size, nprinted, precision,\
- sign_bit, zero_flag, npad, result, res_len);\
+ sign_bit, zero_flag, npad, default_width,\
+ result, res_len);\
}\
}\
@@ -1058,6 +1075,16 @@ get_float_string (st_parameter_dt *dtp,
{
int sign_bit, nprinted;
bool zero_flag;
+ int default_width = 0;
+
+ if (f->u.real.w == DEFAULT_WIDTH)
+ /* This codepath can only be reached with -fdec-format-defaults. The default
+ * values are based on those used in the Oracle Fortran compiler.
+ */
+ {
+ default_width = default_width_for_float (kind);
+ precision = default_precision_for_float (kind);
+ }
switch (kind)
{