[libcxx-commits] [clang] [libcxx] [Clang] Implement CWG2369 "Ordering between constraints and substitution" (PR #102857)

[Younan Zhang via libcxx-commits]

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@@ -1111,12 +1111,57 @@ bool Sema::EnsureTemplateArgumentListConstraints(
   return false;
 }
 
-bool Sema::CheckInstantiatedFunctionTemplateConstraints(
+static bool CheckFunctionConstraintsWithoutInstantiation(
+    Sema &SemaRef, SourceLocation PointOfInstantiation,
+    FunctionTemplateDecl *Template, ArrayRef<TemplateArgument> TemplateArgs,
+    ConstraintSatisfaction &Satisfaction) {
+  SmallVector<const Expr *, 3> TemplateAC;
+  Template->getAssociatedConstraints(TemplateAC);
+  if (TemplateAC.empty()) {
+    Satisfaction.IsSatisfied = true;
+    return false;
+  }
+
+  LocalInstantiationScope Scope(SemaRef);
+
+  FunctionDecl *FD = Template->getTemplatedDecl();
+  // Collect the list of template arguments relative to the 'primary'
+  // template. We need the entire list, since the constraint is completely
+  // uninstantiated at this point.
+
+  // FIXME: Add TemplateArgs through the 'Innermost' parameter once
+  // the refactoring of getTemplateInstantiationArgs() relands.
+  MultiLevelTemplateArgumentList MLTAL;
+  MLTAL.addOuterTemplateArguments(Template, /*Args=*/TemplateArgs,
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zyn0217 wrote:

We would collect outer template arguments in the followed getTemplateInstantiationArgs() call, which is adapted to store them in MLTAL. So the depths should remain relative to the primary, which is what we expected?

https://github.com/llvm/llvm-project/pull/102857