tidy - openmp-use-default-none — Extra Clang Tools 22.0.0git documentation (original) (raw)

Finds OpenMP directives that are allowed to contain a default clause, but either don’t specify it or the clause is specified but with the kind other than none, and suggests to use the default(none) clause.

Using default(none) clause forces developers to explicitly specify data sharing attributes for the variables referenced in the construct, thus making it obvious which variables are referenced, and what is their data sharing attribute, thus increasing readability and possibly making errors easier to spot.

Example¶

// for directive cannot have default clause, no diagnostics. void n0(const int a) { #pragma omp for for (int b = 0; b < a; b++) ; }

// parallel directive.

// parallel directive can have default clause, but said clause is not // specified, diagnosed. void p0_0() { #pragma omp parallel ; // WARNING: OpenMP directive parallel does not specify default // clause. Consider specifying default(none) clause. }

// parallel directive can have default clause, and said clause is // specified, with none kind, all good. void p0_1() { #pragma omp parallel default(none) ; }

// parallel directive can have default clause, and said clause is // specified, but with shared kind, which is not none, diagnose. void p0_2() { #pragma omp parallel default(shared) ; // WARNING: OpenMP directive parallel specifies default(shared) // clause. Consider using default(none) clause instead. }

// parallel directive can have default clause, and said clause is // specified, but with firstprivate kind, which is not none, diagnose. void p0_3() { #pragma omp parallel default(firstprivate) ; // WARNING: OpenMP directive parallel specifies default(firstprivate) // clause. Consider using default(none) clause instead. }