[flang] New implementation for checks for constraints C741 through C750

Authored by Pete Steinfeld <psteinfeld@nvidia.com> on Fri, May 1, 1:00 PM.


[flang] New implementation for checks for constraints C741 through C750

Most of these checks were already implemented, and I just added references to
them to the code and tests. Also, much of this code was already
reviewed in the old flang/f18 GitHub repository, but I didn't get to
merge it before we switched repositories.

I implemented the check for C747 to not allow coarray components in derived
types that are of type C_PTR, C_FUNPTR, or type TEAM_TYPE.

I implemented the check for C748 that requires a data component whose type has
a coarray ultimate component to be a nonpointer, nonallocatable scalar and not
be a coarray.

I implemented the check for C750 that adds additional restrictions to the
bounds expressions of a derived type component that's an array.
These bounds expressions are sepcification expressions as defined in
10.1.11. There was already code in lib/Evaluate/check-expression.cpp to
check semantics for specification expressions, but it did not check for
the extra requirements of C750.

C750 prohibits specification functions, the intrinsic functions
also requires every specification inquiry reference to be a constant
expression, and requires that the value of the bound not depend on the
value of a variable.

To implement these additional checks, I added code to the intrinsic proc
table to get the intrinsic class of a procedure. I also added an
enumeration to distinguish between specification expressions for
derived type component bounds versus for type parameters. I then
changed the code to pass an enumeration value to
"CheckSpecificationExpr()" to indicate that the expression was a bounds
expression and used this value to determine whether to emit an error
message when violations of C750 are found.

I changed the implementation of IsPureProcedure() to handle statement
functions and changed some references in the code that tested for the
PURE attribute to call IsPureProcedure().

I also fixed some unrelated tests that got new errors when I implemented these
new checks.

Reviewers: tskeith, DavidTruby, sscalpone

Subscribers: jfb, llvm-commits

Tags: #llvm, #flang

Differential Revision: https://reviews.llvm.org/D79263

Event Timeline

sscalpone added inline comments.

Do we want to add the variable part of the message at the end instead of in the middle?

I'm not sure how to best make @sscalpone's suggested change with respect to git and Arcanist commands.