https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125984
Bug ID: 125984
Summary: GNAT 16.1.0 generates incorrect code at -O1 for nested
procedure accessing enclosing-scope variables
Product: gcc
Version: 16.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
Assignee: unassigned at gcc dot gnu.org
Reporter: [email protected]
CC: dkm at gcc dot gnu.org
Target Milestone: ---
Created attachment 64850
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64850&action=edit
Main Program and Project File
GNAT 16.1.0 generates incorrect code at -O1 for nested procedure
accessing enclosing-scope variables
Environment:
GNAT 16.1.0 gcc.exe (Rev5, Built by MSYS2 project) 16.1.0 GPRBUILD
2026.0.0 (20260430)
Platform: Windows x86_64 MSYS2 UCRT64
Build command:
gprbuild -PTest.gpr
Observed result:
R:-4.90816800672406E+00 Test Failed
Expected result:
R: 2.45189473169632E+03 Test Ok
Observations:
- Compiling with -O0 produces the expected result.
- Declaring R as Volatile produces the expected result.
- GNAT Pro 23.0 produces the expected result.
- The attached source file is a reduced reproducer derived from a
larger astronomical computation.
- The problem appears related to optimization of a nested procedure
that accesses variables declared in an enclosing scope.
- Rewriting the nested procedure to pass all required values
explicitly as parameters avoids the problem.
- The reproducer fails consistently and deterministically when
compiled with the supplied project file.
