docs: fix: WARNING: Parsing of expression failed. Using fallback parser.

For the future, we can use https://sphinx-fortran.readthedocs.io/ for
Fortran functions which can have optional arguments. However, it's an
additional dependency.

Simplify the function declration.

gcc/fortran/ChangeLog:

	* doc/gfortran/intrinsic-procedures/aint.rst: Simplify function
	  declaration.
	* doc/gfortran/intrinsic-procedures/int.rst: Likewise.
	* doc/gfortran/intrinsic-procedures/anint.rst: Likewise.
	* doc/gfortran/intrinsic-procedures/char.rst: Likewise.
	* doc/gfortran/intrinsic-procedures/real.rst: Likewise.

gcc/fortran/doc/gfortran/intrinsic-procedures/aint.rst

@@ -16,7 +16,7 @@
 AINT --- Truncate to a whole number
 ***********************************
 
-.. function:: AINT(A [, KIND])
+.. function:: AINT(A, KIND)
 
   ``AINT(A [, KIND])`` truncates its argument to a whole number.
 
@@ -75,4 +75,4 @@ AINT --- Truncate to a whole number
        * - ``DINT(A)``
          - ``REAL(8) A``
          - ``REAL(8)``
-         - Fortran 77 and later
+         - Fortran 77 and later

gcc/fortran/doc/gfortran/intrinsic-procedures/anint.rst

@@ -16,7 +16,7 @@
 ANINT --- Nearest whole number
 ******************************
 
-.. function:: ANINT(A [, KIND])
+.. function:: ANINT(A, KIND)
 
   ``ANINT(A [, KIND])`` rounds its argument to the nearest whole number.
 
@@ -73,4 +73,4 @@ ANINT --- Nearest whole number
        * - ``DNINT(A)``
          - ``REAL(8) A``
          - ``REAL(8)``
-         - Fortran 77 and later
+         - Fortran 77 and later

gcc/fortran/doc/gfortran/intrinsic-procedures/char.rst

@@ -12,7 +12,7 @@
 CHAR --- Character conversion function
 **************************************
 
-.. function:: CHAR(I [, KIND])
+.. function:: CHAR(I, KIND)
 
   ``CHAR(I [, KIND])`` returns the character represented by the integer :samp:`{I}`.
 
@@ -68,4 +68,4 @@ CHAR --- Character conversion function
   See also:
     :ref:`ACHAR`,
     :ref:`IACHAR`,
-    :ref:`ICHAR`
+    :ref:`ICHAR`

gcc/fortran/doc/gfortran/intrinsic-procedures/int.rst

@@ -16,7 +16,7 @@
 INT --- Convert to integer type
 *******************************
 
-.. function:: INT(A , KIND))
+.. function:: INT(A, KIND)
 
   Convert to integer type
 
@@ -73,4 +73,4 @@ INT --- Convert to integer type
        * - ``IDINT(A)``
          - ``REAL(8) A``
          - ``INTEGER``
-         - Fortran 77 and later
+         - Fortran 77 and later

gcc/fortran/doc/gfortran/intrinsic-procedures/real.rst

@@ -28,7 +28,7 @@
 REAL --- Convert to real type
 ******************************
 
-.. function:: REAL(A [, KIND])
+.. function:: REAL(A, KIND)
 
   ``REAL(A [, KIND])`` converts its argument :samp:`{A}` to a real type.  The
   ``REALPART`` function is provided for compatibility with :command:`g77`,
@@ -101,4 +101,4 @@ REAL --- Convert to real type
          - Fortran 77 and later
 
   See also:
-    :ref:`DBLE`
+    :ref:`DBLE`