8119fe881d
Original-commit: flang-compiler/f18@f39949fc7d Reviewed-on: https://github.com/flang-compiler/f18/pull/130
3.3 KiB
3.3 KiB
As a general principle, this compiler will accept by default and without complaint many legacy features, extensions to the standard language, and features that have been deleted from the standard, so long as the recognition of those features would not cause a standard-conforming program to be rejected or misinterpreted.
Other non-standard features, which do conflict with the current standard specification of the Fortran programming language, are accepted if enabled by command-line options.
Extensions, deletions, and legacy features supported by default
- Tabs in source
<>
as synonym for.NE.
and/=
$
and@
as legal characters in names- Initialization in type declaration statements using
/values/
- Kind specification with
*
, e.g.REAL*4
DOUBLE COMPLEX
- Signed complex literal constants
- DEC
STRUCTURE
,RECORD
,UNION
, andMAP
- Structure field access with
.field
NCHARACTER
type andNC
Kanji character literalsBYTE
as synonym forINTEGER(KIND=1)
- Quad precision REAL literals with
Q
X
prefix/suffix as synonym forZ
on hexadecimal literalsB
,O
,Z
, andX
accepted as suffixes as well as prefixes- Triplets allowed in array constructors
- Old-style
PARAMETER pi=3.14
statement without parentheses %LOC
,%VAL
, and%REF
- Leading comma allowed before I/O item list
- Empty parentheses allowed in
PROGRAM P()
- Missing parentheses allowed in
FUNCTION F
- Cray based
POINTER(p,x)
- Arithmetic
IF
. (Which branch should NaN take? Fall through?) ASSIGN
statement, assignedGO TO
, and assigned formatPAUSE
statement- Hollerith literals and edit descriptors
NAMELIST
allowed in the execution part- Omitted colons on type declaration statements with attributes
- COMPLEX constructor expression, e.g.
(x+y,z)
+
and-
before all primary expressions, e.g.x*-y
.NOT. .NOT.
acceptedNAME=
as synonym forFILE=
DISPOSE=
- Data edit descriptors without width or other details
D
lines in fixed form as comments or debug codeCONVERT=
on the OPEN statement- Leading semicolons are ignored before any statement that could have a label
- The character
&
in column 1 in fixed form source is a variant form of continuation line.
Extensions supported when enabled by options
- C-style backslash escape sequences in quoted CHARACTER literals (but not Hollerith) [-fbackslash]
- Logical abbreviations
.T.
,.F.
,.N.
,.A.
,.O.
, and.X.
[-flogical-abbreviations] .XOR.
as a synonym for.NEQV.
[-fxor-operator]
Extensions and legacy features deliberately not supported
.LG.
as synonym for.NE.
REDIMENSION
- Allocatable
COMMON
- Expressions in formats
ACCEPT
as synonym forREAD *
TYPE
as synonym forPRINT
ARRAY
as synonym forDIMENSION
VIRTUAL
as synonym forDIMENSION
ENCODE
andDECODE
as synonyms for internal I/OIMPLICIT AUTOMATIC
,IMPLICIT STATIC
- Default exponent of zero, e.g.
3.14159E
- Characters in defined operators that are neither letters nor digits
B
suffix on unquoted octal constantsZ
prefix on unquoted hexadecimal constants