[Clang][Sema] Expression in assumption attribute should be full expression (#150814)

Add missing `ActOnFinishFullExpr` to `BuildCXXAssumeExpr`. We did it
during template instantiation but forgot non-template case.

Author: zwuis

clang/docs/ReleaseNotes.rst

@@ -149,6 +149,8 @@ Bug Fixes to C++ Support
 - Diagnose binding a reference to ``*nullptr`` during constant evaluation. (#GH48665)
 - Suppress ``-Wdeprecated-declarations`` in implicitly generated functions. (#GH147293)
 - Fix a crash when deleting a pointer to an incomplete array (#GH150359).
+- Fix an assertion failure when expression in assumption attribute
+  (``[[assume(expr)]]``) creates temporary objects.
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaStmtAttr.cpp

@@ -795,6 +795,10 @@ ExprResult Sema::BuildCXXAssumeExpr(Expr *Assumption,
   if (Res.isInvalid())
     return ExprError();
 
+  Res = ActOnFinishFullExpr(Res.get(), /*DiscardedValue=*/false);
+  if (Res.isInvalid())
+    return ExprError();
+
   Assumption = Res.get();
   if (Assumption->HasSideEffects(Context))
     Diag(Assumption->getBeginLoc(), diag::warn_assume_side_effects)

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -2270,11 +2270,6 @@ TemplateInstantiator::TransformCXXAssumeAttr(const CXXAssumeAttr *AA) {
   if (!Res.isUsable())
     return AA;
 
-  Res = getSema().ActOnFinishFullExpr(Res.get(),
-                                      /*DiscardedValue=*/false);
-  if (!Res.isUsable())
-    return AA;
-
   if (!(Res.get()->getDependence() & ExprDependence::TypeValueInstantiation)) {
     Res = getSema().BuildCXXAssumeExpr(Res.get(), AA->getAttrName(),
                                        AA->getRange());

clang/test/Parser/cxx23-assume.cpp

@@ -5,7 +5,7 @@ void f(int x, int y) {
   [[assume(1)]];
   [[assume(1.0)]];
   [[assume(1 + 2 == 3)]];
-  [[assume(x ? 1 : 2)]];
+  [[assume(x ? 1 : 2)]]; // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
   [[assume(x && y)]];
   [[assume(true)]] [[assume(true)]];
 

clang/test/SemaCXX/cxx23-assume.cpp

@@ -8,6 +8,14 @@
 struct A{};
 struct B{ explicit operator bool() { return true; } };
 
+// This should be the first test case of this file.
+void IsActOnFinishFullExprCalled() {
+  // Do not add other test cases to this function.
+  // Make sure `ActOnFinishFullExpr` is called and creates `ExprWithCleanups`
+  // to avoid assertion failure.
+  [[assume(B{})]]; // expected-warning {{assumption is ignored because it contains (potential) side-effects}} // ext-warning {{C++23 extension}}
+}
+
 template <bool cond>
 void f() {
   [[assume(cond)]]; // ext-warning {{C++23 extension}}