[clang] Improve source location in binary type traits diagnostics

[Endilll]

This patch takes advantage of a recent NFC change that refactored EvaluateBinaryTypeTrait() to accept TypeSourceInfo instead of QualType c7db450.
Before:

test2.cpp:105:55: error: variable length arrays are not supported in '__is_layout_compatible'
  105 |   static_assert(!__is_layout_compatible(int[n], int[n]));
      |                                                       ^
test2.cpp:125:76: error: incomplete type 'CStructIncomplete' where a complete type is required
  125 |   static_assert(__is_layout_compatible(CStructIncomplete, CStructIncomplete));
      |                                                                            ^

After:

test2.cpp:105:41: error: variable length arrays are not supported in '__is_layout_compatible'
  105 |   static_assert(!__is_layout_compatible(int[n], int[n]));
      |                                         ^
test2.cpp:125:40: error: incomplete type 'CStructIncomplete' where a complete type is required
  125 |   static_assert(__is_layout_compatible(CStructIncomplete, CStructIncomplete));
      |                                        ^

[llvmbot]

@llvm/pr-subscribers-clang

Author: Vlad Serebrennikov (Endilll)

Changes

This patch takes advantage of a recent NFC change that refactored EvaluateBinaryTypeTrait() to accept TypeSourceInfo instead of QualType c7db450.
Before:

test2.cpp:105:55: error: variable length arrays are not supported in '__is_layout_compatible'
  105 |   static_assert(!__is_layout_compatible(int[n], int[n]));
      |                                                       ^
test2.cpp:125:76: error: incomplete type 'CStructIncomplete' where a complete type is required
  125 |   static_assert(__is_layout_compatible(CStructIncomplete, CStructIncomplete));
      |                                                                            ^

After:

test2.cpp:105:41: error: variable length arrays are not supported in '__is_layout_compatible'
  105 |   static_assert(!__is_layout_compatible(int[n], int[n]));
      |                                         ^
test2.cpp:125:40: error: incomplete type 'CStructIncomplete' where a complete type is required
  125 |   static_assert(__is_layout_compatible(CStructIncomplete, CStructIncomplete));
      |                                        ^

---

Full diff: https://github.com/llvm/llvm-project/pull/88097.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaExprCXX.cpp (+12-9)
• (modified) clang/test/SemaCXX/type-traits.cpp (+1)

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index dee6b658cd0054..7d7be27a862c2a 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -5843,7 +5843,7 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, const TypeSourceI
         return false;
 
       if (Self.RequireCompleteType(
-              KeyLoc, RhsT, diag::err_incomplete_type_used_in_type_trait_expr))
+              Rhs->getTypeLoc().getBeginLoc(), RhsT, diag::err_incomplete_type_used_in_type_trait_expr))
         return false;
 
       return BaseInterface->isSuperClassOf(DerivedInterface);
@@ -5866,7 +5866,7 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, const TypeSourceI
     //   If Base and Derived are class types and are different types
     //   (ignoring possible cv-qualifiers) then Derived shall be a
     //   complete type.
-    if (Self.RequireCompleteType(KeyLoc, RhsT,
+    if (Self.RequireCompleteType(Rhs->getTypeLoc().getBeginLoc(), RhsT,
                           diag::err_incomplete_type_used_in_type_trait_expr))
       return false;
 
@@ -5919,7 +5919,7 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, const TypeSourceI
       return LhsT->isVoidType();
 
     // A function definition requires a complete, non-abstract return type.
-    if (!Self.isCompleteType(KeyLoc, RhsT) || Self.isAbstractType(KeyLoc, RhsT))
+    if (!Self.isCompleteType(Rhs->getTypeLoc().getBeginLoc(), RhsT) || Self.isAbstractType(Rhs->getTypeLoc().getBeginLoc(), RhsT))
       return false;
 
     // Compute the result of add_rvalue_reference.
@@ -5969,11 +5969,11 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, const TypeSourceI
     //   For both, T and U shall be complete types, (possibly cv-qualified)
     //   void, or arrays of unknown bound.
     if (!LhsT->isVoidType() && !LhsT->isIncompleteArrayType() &&
-        Self.RequireCompleteType(KeyLoc, LhsT,
+        Self.RequireCompleteType(Lhs->getTypeLoc().getBeginLoc(), LhsT,
           diag::err_incomplete_type_used_in_type_trait_expr))
       return false;
     if (!RhsT->isVoidType() && !RhsT->isIncompleteArrayType() &&
-        Self.RequireCompleteType(KeyLoc, RhsT,
+        Self.RequireCompleteType(Rhs->getTypeLoc().getBeginLoc(), RhsT,
           diag::err_incomplete_type_used_in_type_trait_expr))
       return false;
 
@@ -6029,12 +6029,15 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, const TypeSourceI
   }
   case BTT_IsLayoutCompatible: {
     if (!LhsT->isVoidType() && !LhsT->isIncompleteArrayType())
-      Self.RequireCompleteType(KeyLoc, LhsT, diag::err_incomplete_type);
+      Self.RequireCompleteType(Lhs->getTypeLoc().getBeginLoc(), LhsT, diag::err_incomplete_type);
     if (!RhsT->isVoidType() && !RhsT->isIncompleteArrayType())
-      Self.RequireCompleteType(KeyLoc, RhsT, diag::err_incomplete_type);
+      Self.RequireCompleteType(Rhs->getTypeLoc().getBeginLoc(), RhsT, diag::err_incomplete_type);
 
-    if (LhsT->isVariableArrayType() || RhsT->isVariableArrayType())
-      Self.Diag(KeyLoc, diag::err_vla_unsupported)
+    if (LhsT->isVariableArrayType())
+      Self.Diag(Lhs->getTypeLoc().getBeginLoc(), diag::err_vla_unsupported)
+          << 1 << tok::kw___is_layout_compatible;
+    if (RhsT->isVariableArrayType())
+      Self.Diag(Rhs->getTypeLoc().getBeginLoc(), diag::err_vla_unsupported)
           << 1 << tok::kw___is_layout_compatible;
     return Self.IsLayoutCompatible(LhsT, RhsT);
   }
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
index e29763714341e7..421d3007d27ffe 100644
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -1759,6 +1759,7 @@ void is_layout_compatible(int n)
   // expected-error@-1 {{variable length arrays are not supported in '__is_layout_compatible'}}
   static_assert(!__is_layout_compatible(int[n], int[n]));
   // expected-error@-1 {{variable length arrays are not supported in '__is_layout_compatible'}}
+  // expected-error@-2 {{variable length arrays are not supported in '__is_layout_compatible'}}
   static_assert(__is_layout_compatible(int&, int&));
   static_assert(!__is_layout_compatible(int&, char&));
   static_assert(__is_layout_compatible(void(int), void(int)));

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[tbaederr]

Do we now have enough information to pass a source range as well?

[Endilll]

Do we now have enough information to pass a source range as well?

Yes, TypeLoc inside TypeSourceInfo has two SourceLocation objects that represent the range.
In order to limit the scope of the PR, I'm not refactoring RequireCompleteType and friends to accept TypeSourceInfo, but that's an obvious next step. Diagnostics would benefit from source range.