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fix: use modern array constructor syntax for implied-do loops (fixes #2460) #2485

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Merged
krystophny merged 3 commits into from
Nov 23, 2025
Merged

fix: use modern array constructor syntax for implied-do loops (fixes #2460) #2485

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16025ce
fix: emit modern array constructor syntax for implied-do loops (fixes…
krystophny Nov 23, 2025
f3a9918
test: update implied-do tests to expect modern syntax
krystophny Nov 23, 2025
1d2f602
fix: address review findings (#2485)
krystophny Nov 23, 2025
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22 changes: 11 additions & 11 deletions src/codegen/codegen_expressions_part2.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -267,30 +267,30 @@
step_code = generate_code_from_arena(arena, node%step_expr_index)
step_code = trim(step_code)
if (allocated(node%var_name)) then
inner = "(" // expr_code // ", " // node%var_name // "=" // &
start_code // ", " // end_code // ", " // step_code // ")"
inner = expr_code // ", " // node%var_name // "=" // &
start_code // ", " // end_code // ", " // step_code
else
inner = "(" // expr_code // ", i=" // start_code // ", " // &
end_code // ", " // step_code // ")"
inner = expr_code // ", i=" // start_code // ", " // &
end_code // ", " // step_code
end if
else
if (allocated(node%var_name)) then
inner = "(" // expr_code // ", " // node%var_name // "=" // &
start_code // ", " // end_code // ")"
inner = expr_code // ", " // node%var_name // "=" // &
start_code // ", " // end_code
else
inner = "(" // expr_code // ", i=" // start_code // ", " // &
end_code // ")"
inner = expr_code // ", i=" // start_code // ", " // &
end_code
end if
end if

if (present(type_spec)) then
if (len_trim(type_spec) > 0) then
code = "(/ " // trim(type_spec) // " :: " // trim(inner) // " /)"
code = "[" // trim(type_spec) // " :: (" // trim(inner) // ")]"
else
code = "(/ " // trim(inner) // " /)"
code = "[(" // trim(inner) // ")]"
end if
else
code = "(/ " // trim(inner) // " /)"
code = "[(" // trim(inner) // ")]"
end if
class default
! Not a do loop node - fallback
Expand Down
7 changes: 4 additions & 3 deletions test/frontend/test_issue_1580_dimension_statement.f90
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
program test_issue_1580_dimension_statement
use transformation_api, only: transform_lazy_fortran_string
implicit none

call run_dimension_conversion_test()
print *, ""
Expand Down Expand Up @@ -46,11 +47,11 @@ subroutine run_dimension_conversion_test()
error stop 1
end if

has_assignment = index(output_code, "arr1 = (/(i, i=1,10)/)") > 0
has_assignment = index(output_code, "arr1 = [(i, i=1,10)]") > 0
has_assignment = has_assignment .or. &
index(output_code, "arr1 = (/(i, i=1, 10) /)") > 0
index(output_code, "arr1 = [(i, i=1, 10)]") > 0
has_assignment = has_assignment .or. &
index(output_code, "arr1 = (/(i, i = 1, 10) /)") > 0
index(output_code, "arr1 = [(i, i = 1, 10)]") > 0

if (.not. has_assignment) then
print *, "FAIL: array constructor assignment not preserved"
Expand Down
23 changes: 12 additions & 11 deletions test/integration/feature_tests/test_implied_do_loops.f90
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
program test_implied_do_loops
use transformation_api, only: transform_lazy_fortran_string
implicit none
character(len=:), allocatable :: output, error_msg

write (*, '(A)') "=== Testing Implied Do Loop Array Constructors ==="
Expand All @@ -23,12 +24,12 @@ subroutine test_simple_implied_do()
error stop 1
end if

! The generated code should use legacy (/ /) syntax for compatibility
if (contains_without_spaces(output, "(/(i,i=1,5)/)")) then
! The generated code should use modern [...] syntax for compatibility
if (contains_without_spaces(output, "[(i,i=1,5)]")) then
print *, " PASS: Simple implied do loop"
else
print *, " FAIL: Simple implied do loop - Expected" // &
" (/ (i, i=1, 5) /) syntax"
" [(i, i=1, 5)] syntax"
print *, " Got:", trim(output)
error stop 1
end if
Expand All @@ -45,11 +46,11 @@ subroutine test_complex_implied_do()
error stop 1
end if

if (contains_without_spaces(output, "sum((/(i*2,i=1,10)/))")) then
if (contains_without_spaces(output, "sum([(i*2,i=1,10)])")) then
print *, " PASS: Implied do with expression"
else
print *, " FAIL: Implied do with expression - Expected" // &
" sum((/ (i*2, i=1, 10) /))"
" sum([(i*2, i=1, 10)])"
print *, " Got:", trim(output)
error stop 1
end if
Expand All @@ -58,13 +59,13 @@ end subroutine test_complex_implied_do
subroutine test_nested_implied_do_levels()
character(len=:), allocatable :: input
character(len=*), parameter :: nested2_pattern = &
"reshape((/((i*10+j,j=1,3),i=1,3)/),[3,3])"
"reshape([((i*10+j,j=1,3),i=1,3)],[3,3])"
character(len=*), parameter :: nested3_pattern = &
"reshape((/(((i*100+j*10+k,k=1,3),j=1,3),i=1,3)/),[3,3,3])"
"reshape([(((i*100+j*10+k,k=1,3),j=1,3),i=1,3)],[3,3,3])"
character(len=*), parameter :: nested2_expect = &
"reshape((/((i*10 + j, j=1, 3), i=1, 3) /), [3, 3])"
"reshape([((i*10 + j, j=1, 3), i=1, 3)], [3, 3])"
character(len=*), parameter :: nested3_expect = &
"reshape((/(((i*100 + j*10 + k, k=1, 3), j=1, 3), i=1, 3) /), " // &
"reshape([(((i*100 + j*10 + k, k=1, 3), j=1, 3), i=1, 3)], " // &
"[3, 3, 3])"

input = 'matrix = reshape([((i*10 + j, j=1,3), i=1,3)], [3,3])'
Expand Down Expand Up @@ -114,10 +115,10 @@ subroutine test_nested_function_with_implied_do()
error stop 1
end if

if (contains_without_spaces(output, "(/(sqrt(real(i)),i=1,5)/)")) then
if (contains_without_spaces(output, "[(sqrt(real(i)),i=1,5)]")) then
print *, " PASS: Nested functions with implied do"
else
print *, " FAIL: Nested functions with implied do - Expected legacy syntax"
print *, " FAIL: Nested functions with implied do - Expected modern syntax"
print *, " Got:", trim(output)
error stop 1
end if
Expand Down
2 changes: 1 addition & 1 deletion test/integration/issue_tests/test_issue_1575_implied_do_array_constructor.f90
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Expand Up @@ -20,7 +20,7 @@ program test_issue_1575_implied_do_array_constructor
end if
end if

if (index(transformed, 'arr = (/(i*2, i=1, 10) /)') == 0) then
if (index(transformed, 'arr = [(i*2, i=1, 10)]') == 0) then
print *, 'FAIL: implied-do constructor lost'
print *, 'Output:'
print *, trim(transformed)
Expand Down
2 changes: 1 addition & 1 deletion test/integration/issue_tests/test_issue_1777_negative_stride.f90
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Expand Up @@ -25,7 +25,7 @@ program test_issue_1777_negative_stride
stop 1
end if

if (index(transformed, '(/(i, i=10, 1, -2) /)') == 0) then
if (index(transformed, '[(i, i=10, 1, -2)]') == 0) then
print *, 'FAIL: implied-do with negative stride lost'
print *, 'Output:'
print *, trim(transformed)
Expand Down