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[Clang] Ignore assumptions with side effects at compile time #85534

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Merged
Sirraide merged 1 commit into from
Mar 16, 2024
Merged

[Clang] Ignore assumptions with side effects at compile time #85534

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3 changes: 3 additions & 0 deletions clang/lib/AST/ExprConstant.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5594,6 +5594,9 @@ static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
if (Assumption->isValueDependent())
return ESR_Failed;

if (Assumption->HasSideEffects(Info.getCtx()))
continue;

bool Value;
if (!EvaluateAsBooleanCondition(Assumption, Value, Info))
return ESR_Failed;
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10 changes: 10 additions & 0 deletions clang/test/SemaCXX/cxx23-assume.cpp
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Expand Up @@ -126,3 +126,13 @@ static_assert(f5<D>() == 1); // expected-note 3 {{while checking constraint sati
static_assert(f5<double>() == 2);
static_assert(f5<E>() == 1); // expected-note {{while checking constraint satisfaction}} expected-note {{in instantiation of}}
static_assert(f5<F>() == 2); // expected-note {{while checking constraint satisfaction}} expected-note {{in instantiation of}}

// Do not validate assumptions whose evaluation would have side-effects.
constexpr int foo() {
int a = 0;
[[assume(a++)]] [[assume(++a)]]; // expected-warning 2 {{has side effects that will be discarded}} ext-warning 2 {{C++23 extension}}
[[assume((a+=1))]]; // expected-warning {{has side effects that will be discarded}} ext-warning {{C++23 extension}}
return a;
}

static_assert(foo() == 0);