[clang] 5a560b3 - Revert "[Clang] Preserve more sugars in constraint evaluation" (#163322)
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cfe-commits at lists.llvm.org
Mon Oct 13 23:24:38 PDT 2025
Author: Younan Zhang
Date: 2025-10-14T14:24:34+08:00
New Revision: 5a560b306dbc93c5f9dde3a0a4e39d5d56a287dc
URL: https://github.com/llvm/llvm-project/commit/5a560b306dbc93c5f9dde3a0a4e39d5d56a287dc
DIFF: https://github.com/llvm/llvm-project/commit/5a560b306dbc93c5f9dde3a0a4e39d5d56a287dc.diff
LOG: Revert "[Clang] Preserve more sugars in constraint evaluation" (#163322)
Reverts llvm/llvm-project#162991
That patch breaks certain uses of VLAs when combined with constrained
types.
This is a pre-existing issue that occurs when concepts are instantiated
with sugar. See also #102353 and related PRs. I tried to fix it on top
of the status quo in #163167, but that approach turned out to be
unfeasible, and our maintainer was clearly unhappy with it, hence this
revert.
Even after this patch, some VLA uses remain broken on trunk (see the
example below), because our normalization patch depends on sugar to
correctly compile libc++, due to a very subtle underlying bug. Still,
this is the best attempt to mitigate the problem for now.
We discussed this and agreed that the long-term solution is to remove
the sugar dependencies from concepts, before the VLA issue is properly
resolved through a larger refactoring.
I'll add a related test (which passes with partially applied sugar)
after this revert, since I don't have a reduced example yet.
Added:
Modified:
clang/lib/Sema/SemaConcept.cpp
clang/test/CXX/expr/expr.prim/expr.prim.req/compound-requirement.cpp
clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
clang/test/CXX/temp/temp.param/p10-2a.cpp
clang/test/SemaHLSL/BuiltIns/Buffers.hlsl
clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl
clang/test/SemaTemplate/concepts-recursive-inst.cpp
clang/test/SemaTemplate/concepts.cpp
Removed:
################################################################################
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 7c44efd7b9c1c..9cbd1bd772f6f 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -614,7 +614,8 @@ ConstraintSatisfactionChecker::SubstitutionInTemplateArguments(
for (unsigned I = 0, MappedIndex = 0; I < Used.size(); I++) {
TemplateArgument Arg;
if (Used[I])
- Arg = CTAI.SugaredConverted[MappedIndex++];
+ Arg = S.Context.getCanonicalTemplateArgument(
+ CTAI.SugaredConverted[MappedIndex++]);
if (I < SubstitutedOuterMost.size()) {
SubstitutedOuterMost[I] = Arg;
Offset = I + 1;
diff --git a/clang/test/CXX/expr/expr.prim/expr.prim.req/compound-requirement.cpp b/clang/test/CXX/expr/expr.prim/expr.prim.req/compound-requirement.cpp
index 5f1243a654f54..af2dce81d8a4b 100644
--- a/clang/test/CXX/expr/expr.prim/expr.prim.req/compound-requirement.cpp
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.req/compound-requirement.cpp
@@ -149,7 +149,7 @@ namespace std_example {
template<typename T> constexpr bool is_same_v<T, T> = true;
template<typename T, typename U> concept same_as = is_same_v<T, U>;
- // expected-note at -1 {{because 'is_same_v<int, typename T2::inner>' evaluated to false}}
+ // expected-note at -1 {{because 'is_same_v<int, typename std_example::T2::inner>' evaluated to false}}
static_assert(C1<int>);
static_assert(C1<int*>);
@@ -160,7 +160,7 @@ namespace std_example {
template<typename T> concept C2 =
requires(T x) {
{*x} -> same_as<typename T::inner>;
- // expected-note at -1{{because 'same_as<int, typename T2::inner>' evaluated to false}}
+ // expected-note at -1{{because 'same_as<int, typename std_example::T2::inner>' evaluated to false}}
// expected-note at -2{{because '*x' would be invalid: indirection requires pointer operand ('int' invalid)}}
};
diff --git a/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp b/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
index 9fc4906459373..70a96bed05867 100644
--- a/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
@@ -27,7 +27,7 @@ using r4i = X<void>::r4<int>; // expected-error{{constraints not satisfied for c
// C++ [expr.prim.req.nested] Examples
namespace std_example {
- template<typename U> concept C1 = sizeof(U) == 1; // expected-note{{because 'sizeof(decltype(+t)) == 1' (4 == 1) evaluated to false}}
+ template<typename U> concept C1 = sizeof(U) == 1; // expected-note{{because 'sizeof(int) == 1' (4 == 1) evaluated to false}}
template<typename T> concept D =
requires (T t) {
requires C1<decltype (+t)>; // expected-note{{because 'decltype(+t)' (aka 'int') does not satisfy 'C1'}}
diff --git a/clang/test/CXX/temp/temp.param/p10-2a.cpp b/clang/test/CXX/temp/temp.param/p10-2a.cpp
index 4f192d33ebe7e..c0406f88db5f3 100644
--- a/clang/test/CXX/temp/temp.param/p10-2a.cpp
+++ b/clang/test/CXX/temp/temp.param/p10-2a.cpp
@@ -95,8 +95,8 @@ concept OneOf = (is_same_v<T, Ts> || ...); // #OneOf
// expected-note@#OneOf 3{{because 'is_same_v<int, char[1]>' evaluated to false}}
// expected-note@#OneOf 3{{and 'is_same_v<int, char[2]>' evaluated to false}}
// expected-note@#OneOf {{because 'is_same_v<decltype(nullptr), char>' evaluated to false}}
-// expected-note@#OneOf {{because 'is_same_v<decltype(nullptr), char>' evaluated to false}}
-// expected-note@#OneOf {{and 'is_same_v<decltype(nullptr), int>' evaluated to false}}
+// expected-note@#OneOf {{because 'is_same_v<std::nullptr_t, char>' evaluated to false}}
+// expected-note@#OneOf {{and 'is_same_v<std::nullptr_t, int>' evaluated to false}}
// expected-note@#OneOf {{and 'is_same_v<decltype(nullptr), int>' evaluated to false}}
template<OneOf<char[1], char[2]> T, OneOf<int, long, char> U>
diff --git a/clang/test/SemaHLSL/BuiltIns/Buffers.hlsl b/clang/test/SemaHLSL/BuiltIns/Buffers.hlsl
index 3f0a37d5d5a08..999372c95554e 100644
--- a/clang/test/SemaHLSL/BuiltIns/Buffers.hlsl
+++ b/clang/test/SemaHLSL/BuiltIns/Buffers.hlsl
@@ -20,7 +20,7 @@ Buffer<double2> r4;
// expected-error at +4 {{constraints not satisfied for class template 'Buffer'}}
// expected-note@*:* {{template declaration from hidden source: template <typename element_type> requires __is_typed_resource_element_compatible<element_type> class Buffer}}
// expected-note@*:* {{because 'Buffer<int>' does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(Buffer<int>)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(hlsl::Buffer<int>)' evaluated to false}}
Buffer<Buffer<int> > r5;
struct s {
@@ -66,7 +66,7 @@ Buffer<half[4]> r10;
typedef vector<int, 8> int8;
// expected-error at +3 {{constraints not satisfied for class template 'Buffer'}}
// expected-note@*:* {{because 'int8' (aka 'vector<int, 8>') does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(int8)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(vector<int, 8>)' evaluated to false}}
Buffer<int8> r11;
typedef int MyInt;
@@ -91,7 +91,7 @@ Buffer<numbers> r15;
// expected-error at +3 {{constraints not satisfied for class template 'Buffer'}}
// expected-note@*:* {{because 'double3' (aka 'vector<double, 3>') does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(double3)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(vector<double, 3>)' evaluated to false}}
Buffer<double3> r16;
diff --git a/clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl b/clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl
index aa36c4838273e..b33f2af8a1117 100644
--- a/clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl
+++ b/clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl
@@ -20,7 +20,7 @@ RWBuffer<double2> r4;
// expected-error at +4 {{constraints not satisfied for class template 'RWBuffer'}}
// expected-note@*:* {{template declaration from hidden source: template <typename element_type> requires __is_typed_resource_element_compatible<element_type> class RWBuffer}}
// expected-note@*:* {{because 'RWBuffer<int>' does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(RWBuffer<int>)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(hlsl::RWBuffer<int>)' evaluated to false}}
RWBuffer<RWBuffer<int> > r5;
struct s {
@@ -66,7 +66,7 @@ RWBuffer<half[4]> r10;
typedef vector<int, 8> int8;
// expected-error at +3 {{constraints not satisfied for class template 'RWBuffer'}}
// expected-note@*:* {{because 'int8' (aka 'vector<int, 8>') does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(int8)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(vector<int, 8>)' evaluated to false}}
RWBuffer<int8> r11;
typedef int MyInt;
@@ -91,7 +91,7 @@ RWBuffer<numbers> r15;
// expected-error at +3 {{constraints not satisfied for class template 'RWBuffer'}}
// expected-note@*:* {{because 'double3' (aka 'vector<double, 3>') does not satisfy '__is_typed_resource_element_compatible'}}
-// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(double3)' evaluated to false}}
+// expected-note@*:* {{because '__builtin_hlsl_is_typed_resource_element_compatible(vector<double, 3>)' evaluated to false}}
RWBuffer<double3> r16;
diff --git a/clang/test/SemaTemplate/concepts-recursive-inst.cpp b/clang/test/SemaTemplate/concepts-recursive-inst.cpp
index d36c6a8f02b20..73dce9317f383 100644
--- a/clang/test/SemaTemplate/concepts-recursive-inst.cpp
+++ b/clang/test/SemaTemplate/concepts-recursive-inst.cpp
@@ -68,8 +68,8 @@ struct my_range{
void baz() {
auto it = begin(rng); // #BEGIN_CALL
// expected-error-re@#INF_REQ {{satisfaction of constraint {{.*}} depends on itself}}
-// expected-note@#INF_BEGIN {{while checking the satisfaction of concept 'Inf<struct my_range>' requested here}}
-// expected-note@#INF_BEGIN_EXPR {{while checking constraint satisfaction for template 'begin<struct my_range>' required here}}
+// expected-note@#INF_BEGIN {{while checking the satisfaction of concept 'Inf<DirectRecursiveCheck::my_range>' requested here}}
+// expected-note@#INF_BEGIN_EXPR {{while checking constraint satisfaction for template 'begin<DirectRecursiveCheck::my_range>' required here}}
// expected-note@#INF_BEGIN_EXPR {{while substituting deduced template arguments into function template 'begin'}}
// expected-note@#INF_BEGIN_EXPR {{in instantiation of requirement here}}
// expected-note@#INF_REQ {{while substituting template arguments into constraint expression here}}
diff --git a/clang/test/SemaTemplate/concepts.cpp b/clang/test/SemaTemplate/concepts.cpp
index ee2bb8de66079..3fbe7c0ac650f 100644
--- a/clang/test/SemaTemplate/concepts.cpp
+++ b/clang/test/SemaTemplate/concepts.cpp
@@ -833,13 +833,13 @@ struct Parent {
static_assert(Parent<void>::TakesUnary<int, 0>::i == 0);
// expected-error at +3{{constraints not satisfied for class template 'TakesUnary'}}
// expected-note@#UNARY{{because 'decltype(0ULL)' (aka 'unsigned long long') does not satisfy 'C'}}
-// expected-note@#61777_C{{because 'sizeof(decltype(0ULL)) == 4' (8 == 4) evaluated to false}}
+// expected-note@#61777_C{{because 'sizeof(unsigned long long) == 4' (8 == 4) evaluated to false}}
static_assert(Parent<void>::TakesUnary<int, 0uLL>::i == 0);
static_assert(Parent<int>::TakesBinary<int, 0>::i == 0);
// expected-error at +3{{constraints not satisfied for class template 'TakesBinary'}}
// expected-note@#BINARY{{because 'C2<decltype(0ULL), int>' evaluated to false}}
-// expected-note@#61777_C2{{because 'sizeof(decltype(0ULL)) == sizeof(int)' (8 == 4) evaluated to false}}
+// expected-note@#61777_C2{{because 'sizeof(unsigned long long) == sizeof(int)' (8 == 4) evaluated to false}}
static_assert(Parent<int>::TakesBinary<int, 0ULL>::i == 0);
}
@@ -1329,8 +1329,8 @@ static_assert(__cpp17_iterator<not_move_constructible>); \
// expected-error {{static assertion failed}} \
// expected-note {{because 'not_move_constructible' does not satisfy '__cpp17_iterator'}} \
// expected-note@#__cpp17_copy_constructible {{because 'not_move_constructible' does not satisfy '__cpp17_copy_constructible'}} \
-// expected-note@#__cpp17_move_constructible {{because 'not_move_constructible' does not satisfy '__cpp17_move_constructible'}} \
-// expected-note@#is_move_constructible_v {{because 'is_move_constructible_v<not_move_constructible>' evaluated to false}}
+// expected-note@#__cpp17_move_constructible {{because 'parameter_mapping_regressions::case3::not_move_constructible' does not satisfy '__cpp17_move_constructible'}} \
+// expected-note@#is_move_constructible_v {{because 'is_move_constructible_v<parameter_mapping_regressions::case3::not_move_constructible>' evaluated to false}}
}
namespace case4 {
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