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jgonzac merged 1 commit into from
Oct 27, 2025
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PWR080: Simplify examples to use enumerated options #104

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40 changes: 27 additions & 13 deletions Checks/PWR080/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -56,18 +56,24 @@ them.
Consider the following code, which sums the elements of an array after applying
the specified transformation:

```c {8,24} showLineNumbers
```c {14,30} showLineNumbers
// example.c
#include <stdio.h>
#include <string.h>

double transform_and_sum(const double *array, size_t size, const char *option) {
typedef enum {
OPTION_HALF,
OPTION_DOUBLE,
OPTION_UNKNOWN,
} TransformOption;

double transform_and_sum(const double *array, size_t size,
TransformOption option) {
double sum = 0.0;

double factor;
if (strcmp(option, "half") == 0) {
if (option == OPTION_HALF) {
factor = 0.5;
} else if (strcmp(option, "double") == 0) {
} else if (option == OPTION_DOUBLE) {
factor = 2.0;
}

Expand All @@ -80,7 +86,7 @@ double transform_and_sum(const double *array, size_t size, const char *option) {

int main() {
double array[] = {0.25, 0.25, 0.25, 0.25};
printf("Sum is: %f\n", transform_and_sum(array, 4, "unknownOption"));
printf("Sum is: %f\n", transform_and_sum(array, 4, OPTION_UNKNOWN));

return 0;
}
Expand All @@ -89,7 +95,7 @@ int main() {
Note how `factor`, an automatic variable, is only explicitly initialized when
the received `option` is known. Since the C standard does not guarantee any
specific initial value, the state of `factor` is indeterminate in the previous
scenario (using an `unknownOption`), leading to different outcomes depending on
scenario (using `OPTION_UNKNOWN`), leading to different outcomes depending on
the compiler and its settings:

- For instance, `gcc -O2` behaves as if the `if` branch was taken:
Expand Down Expand Up @@ -136,34 +142,42 @@ double factor = 1.0;
Consider the following code, which sums the elements of an array after applying
the specified transformation:

```fortran {9,20} showLineNumbers
```fortran {17,28} showLineNumbers
! example.f90

module options
integer, parameter :: OPTION_HALF = 1
integer, parameter :: OPTION_DOUBLE = 2
integer, parameter :: OPTION_UNKNOWN = 3
end module options

program main
use iso_fortran_env, only: real32
use options, only: OPTION_HALF, OPTION_DOUBLE, OPTION_UNKNOWN
implicit none

real(kind=real32) :: array(4)
array = [0.25, 0.25, 0.25, 0.25]

print *, "Sum is:", transform_and_sum(array, "unknownOption")
print *, "Sum is:", transform_and_sum(array, OPTION_UNKNOWN)

contains

real(kind=real32) function transform_and_sum(array, option)
implicit none

real(kind=real32), intent(in) :: array(:)
character(len=*), intent(in) :: option
integer, intent(in) :: option

real(kind=real32) :: sum
real(kind=real32) :: factor
integer :: i

sum = 0.0

if (option == "half") then
if (option == OPTION_HALF) then
factor = 0.5
else if (option == "double") then
else if (option == OPTION_DOUBLE) then
factor = 2.0
end if

Expand All @@ -180,7 +194,7 @@ end program main
Note how `factor` is only explicitly initialized when the received `option` is
known. Since the Fortran standard does not guarantee any specific initial
value, the state of `factor` is indeterminate in the previous scenario (using
an `unknownOption`), leading to different outcomes depending on the compiler
`OPTION_UNKNOWN`), leading to different outcomes depending on the compiler
and its settings:

- For instance, `gfortran -O2` behaves as if the `if` branch was taken:
Expand Down
16 changes: 11 additions & 5 deletions Checks/PWR080/example.c
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Original file line number Diff line number Diff line change
@@ -1,15 +1,21 @@
// PWR080: Conditionally initialized variables can lead to undefined behavior

#include <stdio.h>
#include <string.h>

double transform_and_sum(const double *array, size_t size, const char *option) {
typedef enum {
OPTION_HALF,
OPTION_DOUBLE,
OPTION_UNKNOWN,
} TransformOption;

double transform_and_sum(const double *array, size_t size,
TransformOption option) {
double sum = 0.0;

double factor;
if (strcmp(option, "half") == 0) {
if (option == OPTION_HALF) {
factor = 0.5;
} else if (strcmp(option, "double") == 0) {
} else if (option == OPTION_DOUBLE) {
factor = 2.0;
}

Expand All @@ -22,7 +28,7 @@ double transform_and_sum(const double *array, size_t size, const char *option) {

int main() {
double array[] = {0.25, 0.25, 0.25, 0.25};
printf("Sum is: %f\n", transform_and_sum(array, 4, "unknownOption"));
printf("Sum is: %f\n", transform_and_sum(array, 4, OPTION_UNKNOWN));

return 0;
}
15 changes: 11 additions & 4 deletions Checks/PWR080/example.f90
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Original file line number Diff line number Diff line change
@@ -1,31 +1,38 @@
! PWR080: Conditionally initialized variables can lead to undefined behavior

module options
integer, parameter :: OPTION_HALF = 1
integer, parameter :: OPTION_DOUBLE = 2
integer, parameter :: OPTION_UNKNOWN = 3
end module options

program main
use iso_fortran_env, only: real32
use options, only: OPTION_HALF, OPTION_DOUBLE, OPTION_UNKNOWN
implicit none

real(kind=real32) :: array(4)
array = [0.25, 0.25, 0.25, 0.25]

print *, "Sum is:", transform_and_sum(array, "unknownOption")
print *, "Sum is:", transform_and_sum(array, OPTION_UNKNOWN)

contains

real(kind=real32) function transform_and_sum(array, option)
implicit none

real(kind=real32), intent(in) :: array(:)
character(len=*), intent(in) :: option
integer, intent(in) :: option

real(kind=real32) :: sum
real(kind=real32) :: factor
integer :: i

sum = 0.0

if (option == "half") then
if (option == OPTION_HALF) then
factor = 0.5
else if (option == "double") then
else if (option == OPTION_DOUBLE) then
factor = 2.0
end if

Expand Down
16 changes: 11 additions & 5 deletions Checks/PWR080/solution.c
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Original file line number Diff line number Diff line change
@@ -1,16 +1,22 @@
// PWR080: Conditionally initialized variables can lead to undefined behavior

#include <stdio.h>
#include <string.h>

double transform_and_sum(const double *array, size_t size, const char *option) {
typedef enum {
OPTION_HALF,
OPTION_DOUBLE,
OPTION_UNKNOWN,
} TransformOption;

double transform_and_sum(const double *array, size_t size,
TransformOption option) {
double sum = 0.0;

// Identity transformation by default
double factor = 1.0;
if (strcmp(option, "half") == 0) {
if (option == OPTION_HALF) {
factor = 0.5;
} else if (strcmp(option, "double") == 0) {
} else if (option == OPTION_DOUBLE) {
factor = 2.0;
}

Expand All @@ -23,7 +29,7 @@ double transform_and_sum(const double *array, size_t size, const char *option) {

int main() {
double array[] = {0.25, 0.25, 0.25, 0.25};
printf("Sum is: %f\n", transform_and_sum(array, 4, "unknownOption"));
printf("Sum is: %f\n", transform_and_sum(array, 4, OPTION_UNKNOWN));

return 0;
}
15 changes: 11 additions & 4 deletions Checks/PWR080/solution.f90
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Original file line number Diff line number Diff line change
@@ -1,21 +1,28 @@
! PWR080: Conditionally initialized variables can lead to undefined behavior

module options
integer, parameter :: OPTION_HALF = 1
integer, parameter :: OPTION_DOUBLE = 2
integer, parameter :: OPTION_UNKNOWN = 3
end module options

program main
use iso_fortran_env, only: real32
use options, only: OPTION_HALF, OPTION_DOUBLE, OPTION_UNKNOWN
implicit none

real(kind=real32) :: array(4)
array = [0.25, 0.25, 0.25, 0.25]

print *, "Sum is:", transform_and_sum(array, "unknownOption")
print *, "Sum is:", transform_and_sum(array, OPTION_UNKNOWN)

contains

real(kind=real32) function transform_and_sum(array, option)
implicit none

real(kind=real32), intent(in) :: array(:)
character(len=*), intent(in) :: option
integer, intent(in) :: option

real(kind=real32) :: sum
real(kind=real32) :: factor
Expand All @@ -25,9 +32,9 @@ real(kind=real32) function transform_and_sum(array, option)
! Identity transformation by default
factor = 1.0

if (option == "half") then
if (option == OPTION_HALF) then
factor = 0.5
else if (option == "double") then
else if (option == OPTION_DOUBLE) then
factor = 2.0
end if

Expand Down