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[flang] Spurious error with ASSOCIATE in a PURE procedure #131356

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kcooley-cvd opened this issue Mar 14, 2025 · 5 comments · Fixed by #131383
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[flang] Spurious error with ASSOCIATE in a PURE procedure #131356

kcooley-cvd opened this issue Mar 14, 2025 · 5 comments · Fixed by #131383
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@klausler
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flang:frontend release:backport
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LLVM 20.X Release

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@kcooley-cvd
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When given the following code:

MODULE test_m
   REAL :: module_var
CONTAINS
   PURE SUBROUTINE test()
      ASSOCIATE(var => module_var)
      END ASSOCIATE
   END SUBROUTINE test
END MODULE test_m

Flang wrongly announces an error:

./test.f90:14:17: error: A pure subprogram may not have a variable with the SAVE attribute
        ASSOCIATE(var => module_var)
                  ^^^

But test is a valid PURE subroutine since var is not assigned to. Version information:

flang version 20.1.0 (https://github.com/llvm/llvm-project.git 24a30daaa559829ad079f2ff7f73eb4e18095f88)
Target: x86_64-unknown-linux-gnu
Thread model: posix
@llvmbot llvmbot added the flang Flang issues not falling into any other category label Mar 14, 2025
@EugeneZelenko EugeneZelenko added flang:frontend and removed flang Flang issues not falling into any other category labels Mar 14, 2025
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llvmbot commented Mar 14, 2025

@llvm/issue-subscribers-flang-frontend

Author: None (kcooley-cvd)

When given the following code: 
MODULE test_m
   REAL :: module_var
CONTAINS
   PURE SUBROUTINE test()
      ASSOCIATE(var => module_var)
      END ASSOCIATE
   END SUBROUTINE test
END MODULE test_m

Flang wrongly announces an error:

./test.f90:14:17: error: A pure subprogram may not have a variable with the SAVE attribute
        ASSOCIATE(var => module_var)
                  ^^^

But test is a valid PURE subroutine since var is not assigned to. Version information:

flang version 20.1.0 (https://github.com/llvm/llvm-project.git 24a30daaa559829ad079f2ff7f73eb4e18095f88)
Target: x86_64-unknown-linux-gnu
Thread model: posix

@klausler klausler self-assigned this Mar 14, 2025
@klausler
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Thanks for the bug report and its short and clear example! Quick fix coming soon.

klausler added a commit to klausler/llvm-project that referenced this issue Mar 14, 2025
@klausler
[flang] Exempt construct entities from SAVE check for PURE
0176aca 
A PURE subprogram can't have a local variable with the SAVE
attribute.  An ASSOCIATE or SELECT TYPE construct entity whose
selector is a variable will return true from IsSave(); exclude
them from the local variable check.

Fixes llvm#131356.
@klausler klausler mentioned this issue Mar 14, 2025
Merged
klausler added a commit that referenced this issue Mar 19, 2025
@klausler
[flang] Exempt construct entities from SAVE check for PURE (#131383)
b99dab2 
A PURE subprogram can't have a local variable with the SAVE attribute.
An ASSOCIATE or SELECT TYPE construct entity whose selector is a
variable will return true from IsSave(); exclude them from the local
variable check.

Fixes #131356.
llvm-sync bot pushed a commit to arm/arm-toolchain that referenced this issue Mar 19, 2025
@klausler @github-actions
Automerge: [flang] Exempt construct entities from SAVE check for PURE…
e79a278 
… (#131383)

A PURE subprogram can't have a local variable with the SAVE attribute.
An ASSOCIATE or SELECT TYPE construct entity whose selector is a
variable will return true from IsSave(); exclude them from the local
variable check.

Fixes llvm/llvm-project#131356.
@kcooley-cvd
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What is the approximate timeline for this fix to make it into a release?

@tstellar tstellar added this to the LLVM 20.X Release milestone Apr 29, 2025
@github-project-automation github-project-automation bot moved this to Needs Triage in LLVM Release Status Apr 29, 2025
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/cherry-pick b99dab2

@llvmbot
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llvmbot commented Apr 29, 2025

/pull-request #137752

swift-ci pushed a commit to swiftlang/llvm-project that referenced this issue May 9, 2025
@klausler @tstellar
[flang] Exempt construct entities from SAVE check for PURE (llvm#131383)
8272e45 
A PURE subprogram can't have a local variable with the SAVE attribute.
An ASSOCIATE or SELECT TYPE construct entity whose selector is a
variable will return true from IsSave(); exclude them from the local
variable check.

Fixes llvm#131356.

(cherry picked from commit b99dab2)
@tstellar tstellar moved this from Needs Triage to Done in LLVM Release Status May 10, 2025
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@klausler klausler

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flang:frontend release:backport
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Status: Done
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LLVM 20.X Release
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[flang] Exempt construct entities from SAVE check for PURE klausler/llvm-project
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@tstellar @EugeneZelenko @klausler @llvmbot @kcooley-cvd