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[flang][NFC] document BOZ error in DIM, MOD, MODULO, and SIGN (#87779)

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It is highly ambiguous to what type BOZ should be resolved in DIM, MOD,
MODULO, and SIGN intrinsic arguments. Some other compilers accept them,
but none agree. See table below.

List them explicitly as non supported extensions (semantics already
reject them, this is an NFC).

Table listing the resolved types of the intrinsic results when there is
a BOZ argument:

|                     | gfortran | nvfortran | ifort | nagfor | xlf    |
| ------------------- | -------- | --------- | ----- | ------ | ------ |
|  DIM(INT4, BOZ)     |  INT16   |  INT4     |  INT8 | crash  |  INT4  |
|  DIM(BOZ, REAL4)    | error    |  INT8     | error | error  |  REAL4 |
|  DIM(REAL4, BOZ)    | error    |  REAL4    | error | error  |  REAL4 |
|  DIM(BOZ, INT4)     |  INT16   |  INT8     |  INT8 | INT8   |  INT4  |
|  DIM(BOZ, BOZ)      |  INT16   |  INT8     |  INT8 | INT8   |  REAL4 |
|  MOD(INT4, BOZ)     |  INT16   |  INT4     |  INT8 | crash  |  INT4  |
|  MOD(BOZ, REAL4)    | error    |  INT8     | error | error  |  REAL4 |
|  MOD(REAL4, BOZ)    | error    |  REAL4    | error | error  |  REAL4 |
|  MOD(BOZ, INT4)     |  INT16   |  INT8     |  INT8 | INT8   |  INT4  |
|  MOD(BOZ, BOZ)      |  INT16   |  INT8     |  INT8 | INT8   |  INT4  |
|  MODULO(INT4, BOZ)  |  INT16   |  INT4     |  INT8 | crash  |  INT4  |
|  MODULO(BOZ, REAL4) | error    |  INT8     | error | error  |  REAL4 |
|  MODULO(REAL4, BOZ) | error    |  REAL4    | error | error  |  REAL4 |
|  MODULO(BOZ, INT4)  |  INT16   |  INT8     |  INT8 | INT8   |  INT4  |
|  MODULO(BOZ, BOZ)   |  INT16   |  INT8     |  INT8 | INT8   |  INT8  |
|  SIGN(INT4, BOZ)    | error    |  INT4     |  INT8 | INT4   |  INT4  |
|  SIGN(BOZ, REAL4)   | error    |  INT8     | error | error  |  REAL4 |
|  SIGN(REAL4, BOZ)   | error    |  REAL4    | error | error  |  REAL4 |
|  SIGN(BOZ, INT4)    | error    |  INT8     |  INT8 | INT8   |  INT4  |
|  SIGN(BOZ, BOZ)     |  INT16   |  INT8     |  INT8 | INT8   |  REAL4 |
This commit is contained in:
jeanPerier
2024-04-08 10:19:34 +02:00
committed by GitHub
parent 8ddfb66903
commit 3c210d1cfd
1 changed files with 3 additions and 1 deletions
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flang/docs/Extensions.md
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@@ -193,7 +193,9 @@ end
converted. BOZ literals are interpreted as default INTEGER only
when they appear as the first items of array constructors with no
explicit type. Otherwise, they generally cannot be used if the type would
not be known (e.g., `IAND(X'1',X'2')`).
not be known (e.g., `IAND(X'1',X'2')`, or as arguments of `DIM`, `MOD`,
`MODULO`, and `SIGN`. Note that while other compilers may accept such usages,
the type resolution of such BOZ literals usages is highly non portable).
* BOZ literals can also be used as REAL values in some contexts where the
type is unambiguous, such as initializations of REAL parameters.
* EQUIVALENCE of numeric and character sequences (a ubiquitous extension),