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[Clang][Sema]:Fix musttail attribute on a function with not_tail_called attribute has no warning/error #134465

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Merged
merged 9 commits into from
Apr 14, 2025
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[Clang][Sema]:Fix musttail attribute on a function with not_tail_called attribute has no warning/error #134465

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[llvm][Stmt]:git clang format
MillePlateaux Apr 4, 2025
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Add error report
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Error report
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Report error when a musttail call is made to a function marked with t…
MillePlateaux Apr 10, 2025
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#GH134465 Modified version
MillePlateaux Apr 11, 2025
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3 changes: 3 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -325,6 +325,9 @@ Improvements to Clang's diagnostics
- Now correctly diagnose a tentative definition of an array with static
storage duration in pedantic mode in C. (#GH50661)

- The ``-err-musttail-mismatch`` error is emitted when a musttail call is made to a function marked with the not_tail_called attribute.(#133509).
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@AaronBallman AaronBallman Apr 10, 2025

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Suggested change
- The ``-err-musttail-mismatch`` error is emitted when a musttail call is made to a function marked with the not_tail_called attribute.(#133509).
- An error is now emitted when a ``musttail`` call is made to a function marked with the ``not_tail_called`` attribute. (#GH133509).



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@erichkeane erichkeane Apr 14, 2025

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There should only be a single -new-line at the end of this list.

Improvements to Clang's time-trace
----------------------------------

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1 change: 1 addition & 0 deletions clang/include/clang/Basic/DiagnosticSemaKinds.td
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Expand Up @@ -3134,6 +3134,7 @@ def warn_function_attribute_ignored_in_stmt : Warning<
"use '%0' on statements">,
InGroup<IgnoredAttributes>;


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@AaronBallman AaronBallman Apr 10, 2025

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Can back out this whitespace change.

def err_musttail_needs_trivial_args : Error<
"tail call requires that the return value, all parameters, and any "
"temporaries created by the expression are trivially destructible">;
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7 changes: 7 additions & 0 deletions clang/lib/Sema/SemaStmt.cpp
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Expand Up @@ -717,6 +717,13 @@ bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
return false;
}

if (const FunctionDecl *CalleeDecl = CE->getDirectCallee();
CalleeDecl && CalleeDecl->hasAttr<NotTailCalledAttr>()) {
Diag(St->getBeginLoc(), diag::err_musttail_mismatch)
<< &MTA;
return false;
}

if (const auto *EWC = dyn_cast<ExprWithCleanups>(E)) {
if (EWC->cleanupsHaveSideEffects()) {
Diag(St->getBeginLoc(), diag::err_musttail_needs_trivial_args) << &MTA;
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16 changes: 16 additions & 0 deletions clang/test/Sema/attr-musttail.cpp
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@@ -0,0 +1,16 @@
// RUN: %clang_cc1 -verify -fsyntax-only %s

int __attribute__((not_tail_called)) foo1(int a) {
return a + 1;
}


int foo2(int a) {
[[clang::musttail]]
return foo1(a); // expected-error{{cannot perform a tail call to function'musttail' because its signature is incompatible with the calling function}}
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@AaronBallman AaronBallman Apr 10, 2025

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This diagnostic seems odd to me because of function'musttail' Is there really no whitespace there?

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@MillePlateaux MillePlateaux Apr 11, 2025

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This diagnostic seems odd to me because of function'musttail' Is there really no whitespace there?

@AaronBallman Since we reuse err_musttail_mismatch, and the function itself does not have spaces, I tried to add spaces , but the test case did not pass.I've pasted the code below.

def err_musttail_mismatch : Error<
  "cannot perform a tail call to function%select{| %1}0 "
  "because its signature is incompatible with the calling function">;

}

int main() {
int result = foo2(10);
return 0;
}
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@AaronBallman AaronBallman Apr 10, 2025

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Can you add the newline to the end of the file?