[Clang] Ensure correct template parameter depth for abbreviated templates - #209693
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…ates This fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved. This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor. The example comes from 205557.
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@llvm/pr-subscribers-clang Author: Younan Zhang (zyn0217) ChangesThis fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved. This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor. The example comes from 205557. Full diff: https://github.com/llvm/llvm-project/pull/209693.diff 2 Files Affected:
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 893989bd2398f..d7a9c72eb2da8 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2534,6 +2534,12 @@ bool Parser::ParseCXXMemberDeclaratorBeforeInitializer(
if (BitfieldSize.isInvalid())
SkipUntil(tok::comma, StopAtSemi | StopBeforeMatch);
} else if (Tok.is(tok::kw_requires)) {
+ TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
+ // With abbreviated function templates - we need to explicitly add depth to
+ // account for the implicit template parameter list induced by the template.
+ if (DeclaratorInfo.getTemplateParameterLists().empty() &&
+ DeclaratorInfo.getInventedTemplateParameterList())
+ ++CurTemplateDepthTracker;
ParseTrailingRequiresClauseWithScope(DeclaratorInfo);
} else {
ParseOptionalCXX11VirtSpecifierSeq(
diff --git a/clang/test/SemaCXX/constexpr-late-instantiation.cpp b/clang/test/SemaCXX/constexpr-late-instantiation.cpp
index 9aec0c90e61dc..94f5ab4a73616 100644
--- a/clang/test/SemaCXX/constexpr-late-instantiation.cpp
+++ b/clang/test/SemaCXX/constexpr-late-instantiation.cpp
@@ -1,5 +1,10 @@
-// RUN: %clang_cc1 %s -fsyntax-only -verify
-// RUN: %clang_cc1 %s -fexperimental-new-constant-interpreter -fsyntax-only -verify
+// RUN: %clang_cc1 %s -std=c++14 -fsyntax-only -verify
+// RUN: %clang_cc1 %s -std=c++20 -fsyntax-only -verify
+// RUN: %clang_cc1 %s -std=c++2c -fsyntax-only -verify
+
+// RUN: %clang_cc1 %s -std=c++14 -fsyntax-only -fexperimental-new-constant-interpreter -verify
+// RUN: %clang_cc1 %s -std=c++20 -fsyntax-only -fexperimental-new-constant-interpreter -verify
+// RUN: %clang_cc1 %s -std=c++2c -fsyntax-only -fexperimental-new-constant-interpreter -verify
template <typename T>
constexpr T foo(T a); // expected-note {{declared here}}
@@ -14,3 +19,28 @@ template <typename T>
constexpr T foo(T a) {
return a;
}
+
+#if __cplusplus > 202002L
+
+namespace GH115118 {
+
+struct foo {
+ // expected-note@-1 2{{while}}
+ foo(const foo&) = default;
+ foo(auto)
+ requires([]<int = 0>() -> bool { return true; }())
+ // expected-error@-1 {{non-constant expression}}
+ // expected-note@-2 {{undefined function}} \
+ // expected-note@-2 {{declared}}
+ {}
+};
+
+// FIXME: This will be fixed by https://github.com/llvm/llvm-project/pull/205557
+struct bar {
+ // expected-note@-1 {{while}}
+ foo x; // check that the lambda gets instantiated.
+};
+
+} // namespace GH115118
+
+#endif
|
zyn0217
commented
Jul 15, 2026
Comment on lines
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+44
| #if __cplusplus > 202002L | ||
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| namespace GH115118 { | ||
|
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||
| struct foo { | ||
| // expected-note@-1 2{{while}} | ||
| foo(const foo&) = default; | ||
| foo(auto) | ||
| requires([]<int = 0>() -> bool { return true; }()) | ||
| // expected-error@-1 {{non-constant expression}} | ||
| // expected-note@-2 {{undefined function}} \ | ||
| // expected-note@-2 {{declared}} | ||
| {} | ||
| }; | ||
|
|
||
| // FIXME: This will be fixed by https://github.com/llvm/llvm-project/pull/205557 | ||
| struct bar { | ||
| // expected-note@-1 {{while}} | ||
| foo x; // check that the lambda gets instantiated. | ||
| }; | ||
|
|
||
| } // namespace GH115118 |
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@katzdm I stole your test case here, so we don't have duplicated tests
cor3ntin
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This change needs a release note.
Please add an entry to clang/docs/ReleaseNotes.md in the section the most adapted to the change, and referencing any Github issue this change fixes. Thanks!
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FYI I'm going to backport it because the assertion is introduced in clang 23 - we should have already suffered from the incorrect depth earlier but nothing fired. |
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/cherry-pick 3485d85 |
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/pull-request #209712 |
pedroMVicente
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Jul 15, 2026
…ates (llvm#209693) This fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved. This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor. The example comes from llvm#205557.
dyung
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Jul 16, 2026
…ates (llvm#209693) This fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved. This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor. The example comes from llvm#205557. (cherry picked from commit 3485d85)
dyung
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that referenced
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Jul 22, 2026
…ates (llvm#209693) This fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved. This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor. The example comes from llvm#205557. (cherry picked from commit 3485d85)
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This fixes another case of member functions where we overlooked template depths when only abbreviated template parameters are involved.
This mirrors previous fix cfb2520, but I don't intend to put it in ParseTrailingRequiresClause because we might want the similar fix for e.g. noexcept expressions, so let's keep it inline for future refactor.
The example comes from #205557.