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[flang] Better error handling for PDT constant expression (#130637)

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We currently don't consider an integer division to be a constant
expression unless its divisor is known and nonzero. This produces a
weird result in the linked test; do better.

Fixes https://github.com/llvm/llvm-project/issues/130534.
This commit is contained in:
Peter Klausler 2025-03-10 16:48:54 -07:00 committed by GitHub
parent af62a6f59a
commit 016557fab2
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4 changed files with 25 additions and 6 deletions
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7
flang/lib/Evaluate/check-expression.cpp
View file

@ -69,13 +69,14 @@ public:
bool operator()(const Component &component) const {
return (*this)(component.base());
}
// Forbid integer division by zero in constants.
// Prevent integer division by known zeroes in constant expressions.
template <int KIND>
bool operator()(
const Divide<Type<TypeCategory::Integer, KIND>> &division) const {
using T = Type<TypeCategory::Integer, KIND>;
if (const auto divisor{GetScalarConstantValue<T>(division.right())}) {
return !divisor->IsZero() && (*this)(division.left());
if ((*this)(division.left()) && (*this)(division.right())) {
const auto divisor{GetScalarConstantValue<T>(division.right())};
return !divisor || !divisor->IsZero();
} else {
return false;
}

11
flang/lib/Semantics/type.cpp
View file

@ -567,11 +567,18 @@ const DeclTypeSpec &InstantiateHelper::InstantiateIntrinsicType(
kind = *value;
} else {
foldingContext().messages().Say(symbolName,
"KIND parameter value (%jd) of intrinsic type %s "
"did not resolve to a supported value"_err_en_US,
"KIND parameter value (%jd) of intrinsic type %s did not resolve to a supported value"_err_en_US,
*value,
parser::ToUpperCaseLetters(EnumToString(intrinsic.category())));
}
} else {
std::string exprString;
llvm::raw_string_ostream sstream(exprString);
copy.AsFortran(sstream);
foldingContext().messages().Say(symbolName,
"KIND parameter expression (%s) of intrinsic type %s did not resolve to a constant value"_err_en_US,
exprString,
parser::ToUpperCaseLetters(EnumToString(intrinsic.category())));
}
switch (spec.category()) {
case DeclTypeSpec::Numeric:

11
flang/test/Semantics/pdt04.f90 Normal file
View file

@ -0,0 +1,11 @@
!RUN: not %flang_fc1 %s 2>&1 | FileCheck %s
!CHECK: error: KIND parameter expression (int(1_4/0_4,kind=8)) of intrinsic type CHARACTER did not resolve to a constant value
!CHECK: in the context: instantiation of parameterized derived type 'ty(j=1_4,k=0_4)'
!CHECK: warning: INTEGER(4) division by zero
program main
type ty(j,k)
integer, kind :: j, k
character(kind=j/k) a
end type
type(ty(1,0)) x
end

2
flang/test/Semantics/resolve105.f90
View file

@ -1,9 +1,9 @@
! RUN: %python %S/test_errors.py %s %flang_fc1
! Test instantiation of components that are procedure pointers.
!
program test
type dtype(kindParam)
integer, kind :: kindParam = 4
!ERROR: KIND parameter expression (kindparam) of intrinsic type REAL did not resolve to a constant value
!ERROR: KIND parameter value (66) of intrinsic type REAL did not resolve to a supported value
!ERROR: KIND parameter value (55) of intrinsic type REAL did not resolve to a supported value
procedure (real(kindParam)), pointer, nopass :: field => null()