[all-commits] [llvm/llvm-project] 40ad00: [flang] Define array named constants from the iso_...

[mleair via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 40ad00beb3e275e1c50d6a718800d197a6b02c4e
      https://github.com/llvm/llvm-project/commit/40ad00beb3e275e1c50d6a718800d197a6b02c4e
  Author: mleair <leairmark at gmail.com>
  Date:   2026-06-02 (Tue, 02 Jun 2026)

  Changed paths:
    M flang/lib/Lower/Bridge.cpp
    A flang/test/Lower/intrinsic-module-array-constant.f90

  Log Message:
  -----------
  [flang] Define array named constants from the iso_fortran_env intrins… (#201190)

…ic module

createIntrinsicModuleDefinitions() only emitted definitions for array
named constants belonging to the __fortran_ieee_exceptions intrinsic
module. Array constants declared directly in the iso_fortran_env
intrinsic module -- in practice character_kinds -- were therefore only
lowered as bodyless `fir.global` external declarations at their use site
and never defined anywhere, producing an undefined reference at link
time.

This is usually hidden because scalar iso_fortran_env parameters fold to
immediates and constant-shape array accesses are folded away, so the
dangling external symbol is DCE'd before linking. It surfaces when the
address of the array genuinely escapes to runtime, e.g.:
```
    use iso_fortran_env
    integer :: i, x(1)
    do i = 1, size(character_kinds)
      x = findloc(character_kinds, character_kinds(i))
    end do
```
which fails with:

    undefined reference to `_QMiso_fortran_envECcharacter_kinds'

Fix by also processing the iso_fortran_env scope in
createIntrinsicModuleDefinitions(), so its array constants are emitted
as linkonce_odr definitions with initializers.

Note that integer_kinds/real_kinds/logical_kinds are unaffected: they
are renamed from iso_fortran_env_impl, a non-intrinsic module that is
compiled into the runtime, so their definitions already exist there.

Assisted-by: AI



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