[Clang][NFCI] Prefer non-canonical template arguments for synthesized CTAD guides #99840
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… CTAD guides This seems to be low-hanging fruit: We could remove all calls to 'Context.getCanonicalTemplateArgument()' and gain a better diagnostic/AST. The non-canonical template arguments shouldn't make a difference when synthesizing a CTAD guide, so this is intended to be an NFC.
zyn0217
added
the
clang:frontend
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@llvm/pr-subscribers-clang Author: Younan Zhang (zyn0217) ChangesThis seems to be low-hanging fruit: We could remove all calls to The non-canonical template arguments shouldn't make a difference when synthesizing a CTAD guide, so this is intended to be an NFC. Closes #79798 Patch is 28.87 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/99840.diff 5 Files Affected:
diff --git a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
index 7dff2c8f98589..0602d07c6b9b0 100644
--- a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
+++ b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
@@ -363,8 +363,7 @@ struct ConvertConstructorToDeductionGuideTransform {
return nullptr;
// Constraints require that we substitute depth-1 arguments
// to match depths when substituted for evaluation later
- Depth1Args.push_back(SemaRef.Context.getCanonicalTemplateArgument(
- SemaRef.Context.getInjectedTemplateArg(NewParam)));
+ Depth1Args.push_back(SemaRef.Context.getInjectedTemplateArg(NewParam));
if (NestedPattern) {
TemplateDeclInstantiator Instantiator(SemaRef, DC,
@@ -379,8 +378,7 @@ struct ConvertConstructorToDeductionGuideTransform {
"Unexpected template parameter depth");
AllParams.push_back(NewParam);
- SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
- SemaRef.Context.getInjectedTemplateArg(NewParam)));
+ SubstArgs.push_back(SemaRef.Context.getInjectedTemplateArg(NewParam));
}
// Substitute new template parameters into requires-clause if present.
@@ -795,8 +793,8 @@ buildAssociatedConstraints(Sema &SemaRef, FunctionTemplateDecl *F,
/*NewIndex=*/AdjustedAliasTemplateArgs.size(),
getTemplateParameterDepth(TP) + AdjustDepth);
- auto NewTemplateArgument = Context.getCanonicalTemplateArgument(
- Context.getInjectedTemplateArg(NewParam));
+ TemplateArgument NewTemplateArgument =
+ Context.getInjectedTemplateArg(NewParam);
AdjustedAliasTemplateArgs.push_back(NewTemplateArgument);
}
// Template arguments used to transform the template arguments in
@@ -822,8 +820,8 @@ buildAssociatedConstraints(Sema &SemaRef, FunctionTemplateDecl *F,
getTemplateParameterDepth(TP) + AdjustDepth);
FirstUndeducedParamIdx += 1;
assert(TemplateArgsForBuildingRC[Index].isNull());
- TemplateArgsForBuildingRC[Index] = Context.getCanonicalTemplateArgument(
- Context.getInjectedTemplateArg(NewParam));
+ TemplateArgsForBuildingRC[Index] =
+ Context.getInjectedTemplateArg(NewParam);
continue;
}
TemplateArgumentLoc Input =
@@ -923,8 +921,8 @@ Expr *buildIsDeducibleConstraint(Sema &SemaRef,
/*NewIndex=*/TransformedTemplateArgs.size(),
getTemplateParameterDepth(TP) + AdjustDepth);
- auto NewTemplateArgument = Context.getCanonicalTemplateArgument(
- Context.getInjectedTemplateArg(NewParam));
+ TemplateArgument NewTemplateArgument =
+ Context.getInjectedTemplateArg(NewParam);
TransformedTemplateArgs.push_back(NewTemplateArgument);
}
// Transformed the ReturnType to restore the uninstantiated depth.
@@ -1087,8 +1085,8 @@ BuildDeductionGuideForTypeAlias(Sema &SemaRef,
getTemplateParameterDepth(TP));
FPrimeTemplateParams.push_back(NewParam);
- auto NewTemplateArgument = Context.getCanonicalTemplateArgument(
- Context.getInjectedTemplateArg(NewParam));
+ TemplateArgument NewTemplateArgument =
+ Context.getInjectedTemplateArg(NewParam);
TransformedDeducedAliasArgs[AliasTemplateParamIdx] = NewTemplateArgument;
}
unsigned FirstUndeducedParamIdx = FPrimeTemplateParams.size();
@@ -1109,8 +1107,7 @@ BuildDeductionGuideForTypeAlias(Sema &SemaRef,
assert(TemplateArgsForBuildingFPrime[FTemplateParamIdx].isNull() &&
"The argument must be null before setting");
TemplateArgsForBuildingFPrime[FTemplateParamIdx] =
- Context.getCanonicalTemplateArgument(
- Context.getInjectedTemplateArg(NewParam));
+ Context.getInjectedTemplateArg(NewParam);
}
// To form a deduction guide f' from f, we leverage clang's instantiation
diff --git a/clang/test/AST/ast-dump-ctad-alias.cpp b/clang/test/AST/ast-dump-ctad-alias.cpp
index a088c0a7b0272..b1631f7822ce0 100644
--- a/clang/test/AST/ast-dump-ctad-alias.cpp
+++ b/clang/test/AST/ast-dump-ctad-alias.cpp
@@ -32,22 +32,24 @@ Out2<double>::AInner t(1.0);
// CHECK-NEXT: | | |-UnresolvedLookupExpr {{.*}} '<dependent type>' lvalue (no ADL) = 'Concept'
// CHECK-NEXT: | | | |-TemplateArgument type 'int'
// CHECK-NEXT: | | | | `-BuiltinType {{.*}} 'int'
-// CHECK-NEXT: | | | `-TemplateArgument type 'type-parameter-1-0'
-// CHECK-NEXT: | | | `-TemplateTypeParmType {{.*}} 'type-parameter-1-0' dependent depth 1 index 0
+// CHECK-NEXT: | | | `-TemplateArgument type 'Y':'type-parameter-1-0'
+// CHECK-NEXT: | | | `-TemplateTypeParmType {{.*}} 'Y' dependent depth 1 index 0
+// CHECK-NEXT: | | | `-TemplateTypeParm {{.*}} 'Y'
// CHECK-NEXT: | | `-TypeTraitExpr {{.*}} 'bool' __is_deducible
// CHECK-NEXT: | | |-DeducedTemplateSpecializationType {{.*}} 'Out2<double>::AInner' dependent
// CHECK-NEXT: | | | `-name: 'Out2<double>::AInner'
// CHECK-NEXT: | | | `-TypeAliasTemplateDecl {{.+}} AInner{{$}}
-// CHECK-NEXT: | | `-ElaboratedType {{.*}} 'Inner<type-parameter-1-0>' sugar dependent
-// CHECK-NEXT: | | `-TemplateSpecializationType {{.*}} 'Inner<type-parameter-1-0>' dependent
+// CHECK-NEXT: | | `-ElaboratedType {{.*}} 'Inner<Y>' sugar dependent
+// CHECK-NEXT: | | `-TemplateSpecializationType {{.*}} 'Inner<Y>' dependent
// CHECK-NEXT: | | |-name: 'Inner':'Out<int>::Inner' qualified
// CHECK-NEXT: | | | `-ClassTemplateDecl {{.+}} Inner{{$}}
-// CHECK-NEXT: | | `-TemplateArgument type 'type-parameter-1-0'
-// CHECK-NEXT: | | `-SubstTemplateTypeParmType {{.*}} 'type-parameter-1-0'
+// CHECK-NEXT: | | `-TemplateArgument type 'Y'
+// CHECK-NEXT: | | `-SubstTemplateTypeParmType {{.*}} 'Y'
// CHECK-NEXT: | | |-FunctionTemplate {{.*}} '<deduction guide for Inner>'
-// CHECK-NEXT: | | `-TemplateTypeParmType {{.*}} 'type-parameter-1-0' dependent depth 1 index 0
-// CHECK-NEXT: | |-CXXDeductionGuideDecl {{.*}} <deduction guide for AInner> 'auto (type-parameter-0-0) -> Inner<type-parameter-0-0>'
-// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'type-parameter-0-0'
+// CHECK-NEXT: | | `-TemplateTypeParmType {{.*}} 'Y' dependent depth 1 index 0
+// CHECK-NEXT: | | `-TemplateTypeParm {{.*}} 'Y'
+// CHECK-NEXT: | |-CXXDeductionGuideDecl {{.*}} <deduction guide for AInner> 'auto (Y) -> Inner<Y>'
+// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'Y'
// CHECK-NEXT: | `-CXXDeductionGuideDecl {{.*}} used <deduction guide for AInner> 'auto (double) -> Inner<double>' implicit_instantiation
// CHECK-NEXT: | |-TemplateArgument type 'double'
// CHECK-NEXT: | | `-BuiltinType {{.*}} 'double'
@@ -77,8 +79,8 @@ AFoo3 afoo3{0, 1};
// CHECK-NEXT: | |-UnresolvedLookupExpr {{.*}} '<dependent type>' lvalue (no ADL) = 'Concept'
// CHECK-NEXT: | | |-TemplateArgument type 'int'
// CHECK-NEXT: | | | `-BuiltinType {{.*}} 'int'
-// CHECK-NEXT: | | `-TemplateArgument type 'type-parameter-0-1'
-// CHECK-NEXT: | | `-TemplateTypeParmType {{.*}} 'type-parameter-0-1' dependent depth 0 index 1
+// CHECK-NEXT: | | `-TemplateArgument type 'V'
+// CHECK-NEXT: | | `-TemplateTypeParmType {{.*}} 'V' dependent depth 0 index 1
template <typename... T1>
struct Foo {
@@ -88,16 +90,16 @@ struct Foo {
template <typename...T2>
using AFoo = Foo<T2...>;
AFoo a(1, 2);
-// CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for AFoo> 'auto (type-parameter-0-0...) -> Foo<type-parameter-0-0...>'
-// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'type-parameter-0-0...' pack
+// CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for AFoo> 'auto (T2...) -> Foo<T2...>'
+// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'T2...' pack
// CHECK-NEXT: | `-CXXDeductionGuideDecl {{.*}} implicit used <deduction guide for AFoo> 'auto (int, int) -> Foo<int, int>' implicit_instantiation
template <typename T>
using BFoo = Foo<T, T>;
BFoo b2(1.0, 2.0);
-// CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for BFoo> 'auto (type-parameter-0-0, type-parameter-0-0) -> Foo<type-parameter-0-0, type-parameter-0-0>'
-// CHECK-NEXT: | | |-ParmVarDecl {{.*}} 'type-parameter-0-0'
-// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'type-parameter-0-0'
+// CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for BFoo> 'auto (T, T) -> Foo<T, T>'
+// CHECK-NEXT: | | |-ParmVarDecl {{.*}} 'T'
+// CHECK-NEXT: | | `-ParmVarDecl {{.*}} 'T'
// CHECK-NEXT: | `-CXXDeductionGuideDecl {{.*}} implicit used <deduction guide for BFoo> 'auto (double, double) -> Foo<double, double>' implicit_instantiation
namespace GH90209 {
diff --git a/clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p3-0x.cpp b/clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p3-0x.cpp
index ed445360c4fdd..b9ff26a7620db 100644
--- a/clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p3-0x.cpp
+++ b/clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p3-0x.cpp
@@ -78,7 +78,7 @@ namespace std_example {
template<class T> struct A { // expected-note {{candidate}} expected-note {{implicit deduction guide}}
template<class U>
A(T &&, U &&, int *); // expected-note {{[with T = int, U = int] not viable: expects an rvalue}} \
- // expected-note {{implicit deduction guide declared as 'template <class T, class U> A(T &&, type-parameter-0-1 &&, int *) -> A<T>'}}
+ // expected-note {{implicit deduction guide declared as 'template <class T, class U> A(T &&, U &&, int *) -> A<T>'}}
A(T &&, int *); // expected-note {{requires 2}} \
// expected-note {{implicit deduction guide declared as 'template <class T> A(T &&, int *) -> A<T>'}}
};
diff --git a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
index 2193be03ad9a3..5392573fcdb9d 100644
--- a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
+++ b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp
@@ -110,8 +110,8 @@ struct Foo {
template <typename X, int Y>
using Bar = Foo<X, sizeof(X)>; // expected-note {{candidate template ignored: couldn't infer template argument 'X'}} \
- // expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, Foo<type-parameter-0-0, sizeof(type-parameter-0-0)>) Bar(Foo<type-parameter-0-0, sizeof(type-parameter-0-0)>) -> Foo<type-parameter-0-0, sizeof(type-parameter-0-0)>'}} \
- // expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, Foo<type-parameter-0-0, sizeof(type-parameter-0-0)>) Bar(const type-parameter-0-0 (&)[sizeof(type-parameter-0-0)]) -> Foo<type-parameter-0-0, sizeof(type-parameter-0-0)>'}} \
+ // expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, Foo<X, sizeof(X)>) Bar(Foo<X, sizeof(X)>) -> Foo<X, sizeof(X)>'}} \
+ // expected-note {{implicit deduction guide declared as 'template <typename X> requires __is_deducible(test9::Bar, Foo<X, sizeof(X)>) Bar(const X (&)[sizeof(X)]) -> Foo<X, sizeof(X)>'}} \
// expected-note {{candidate template ignored: constraints not satisfied [with X = int]}} \
// expected-note {{cannot deduce template arguments for 'Bar' from 'Foo<int, 4UL>'}}
@@ -138,13 +138,13 @@ namespace test11 {
struct A {};
template<class T> struct Foo { T c; };
template<class X, class Y=A>
-using AFoo = Foo<Y>; // expected-note {{candidate template ignored: could not match 'Foo<type-parameter-0-0>' against 'int'}} \
- // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<type-parameter-0-0>) AFoo(Foo<type-parameter-0-0>) -> Foo<type-parameter-0-0>'}} \
+using AFoo = Foo<Y>; // expected-note {{candidate template ignored: could not match 'Foo<Y>' against 'int'}} \
+ // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<Y>) AFoo(Foo<Y>) -> Foo<Y>'}} \
// expected-note {{candidate template ignored: constraints not satisfied [with Y = int]}} \
// expected-note {{cannot deduce template arguments for 'AFoo' from 'Foo<int>'}} \
- // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<type-parameter-0-0>) AFoo(type-parameter-0-0) -> Foo<type-parameter-0-0>'}} \
+ // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<Y>) AFoo(Y) -> Foo<Y>'}} \
// expected-note {{candidate function template not viable: requires 0 arguments, but 1 was provided}} \
- // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<type-parameter-0-0>) AFoo() -> Foo<type-parameter-0-0>'}}
+ // expected-note {{implicit deduction guide declared as 'template <class Y = A> requires __is_deducible(test11::AFoo, Foo<Y>) AFoo() -> Foo<Y>'}}
AFoo s = {1}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'AFoo'}}
} // namespace test11
@@ -211,9 +211,9 @@ template<typename> concept False = false;
template<False W>
using BFoo = AFoo<W>; // expected-note {{candidate template ignored: constraints not satisfied [with V = int]}} \
// expected-note {{cannot deduce template arguments for 'BFoo' from 'Foo<int *>'}} \
- // expected-note {{implicit deduction guide declared as 'template <class V> requires __is_deducible(AFoo, Foo<type-parameter-0-0 *>) && __is_deducible(test15::BFoo, Foo<type-parameter-0-0 *>) BFoo(type-parameter-0-0 *) -> Foo<type-parameter-0-0 *>}} \
- // expected-note {{candidate template ignored: could not match 'Foo<type-parameter-0-0 *>' against 'int *'}} \
- // expected-note {{template <class V> requires __is_deducible(AFoo, Foo<type-parameter-0-0 *>) && __is_deducible(test15::BFoo, Foo<type-parameter-0-0 *>) BFoo(Foo<type-parameter-0-0 *>) -> Foo<type-parameter-0-0 *>}}
+ // expected-note {{implicit deduction guide declared as 'template <class V> requires __is_deducible(AFoo, Foo<V *>) && __is_deducible(test15::BFoo, Foo<V *>) BFoo(V *) -> Foo<V *>}} \
+ // expected-note {{candidate template ignored: could not match 'Foo<V *>' against 'int *'}} \
+ // expected-note {{template <class V> requires __is_deducible(AFoo, Foo<V *>) && __is_deducible(test15::BFoo, Foo<V *>) BFoo(Foo<V *>) -> Foo<V *>}}
int i = 0;
AFoo a1(&i); // OK, deduce Foo<int *>
@@ -263,12 +263,12 @@ template<typename T> requires False<T> // expected-note {{because 'int' does not
Foo(T) -> Foo<int>;
template <typename U>
-using Bar = Foo<U>; // expected-note {{could not match 'Foo<type-parameter-0-0>' against 'int'}} \
- // expected-note {{implicit deduction guide declared as 'template <typename U> requires __is_deducible(test18::Bar, Foo<type-parameter-0-0>) Bar(Foo<type-parameter-0-0>) -> Foo<type-parameter-0-0>'}} \
+using Bar = Foo<U>; // expected-note {{could not match 'Foo<U>' against 'int'}} \
+ // expected-note {{implicit deduction guide declared as 'template <typename U> requires __is_deducible(test18::Bar, Foo<U>) Bar(Foo<U>) -> Foo<U>'}} \
// expected-note {{candidate template ignored: constraints not satisfied}} \
- // expected-note {{implicit deduction guide declared as 'template <typename T> requires False<type-parameter-0-0> && __is_deducible(test18::Bar, Foo<int>) Bar(type-parameter-0-0) -> Foo<int>'}} \
+ // expected-note {{implicit deduction guide declared as 'template <typename T> requires False<T> && __is_deducible(test18::Bar, Foo<int>) Bar(T) -> Foo<int>'}} \
// expected-note {{candidate function template not viable}} \
- // expected-note {{implicit deduction guide declared as 'template <typename U> requires __is_deducible(test18::Bar, Foo<type-parameter-0-0>) Bar() -> Foo<type-parameter-0-0>'}}
+ // expected-note {{implicit deduction guide declared as 'template <typename U> requires __is_deducible(test18::Bar, Foo<U>) Bar() -> Foo<U>'}}
Bar s = {1}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments}}
} // namespace test18
@@ -296,8 +296,8 @@ class Foo {};
// Verify that template template type parameter TTP is referenced/used in the
// template arguments of the RHS.
template <template<typename> typename TTP>
-using Bar = Foo<K<TTP>>; // expected-note {{candidate template ignored: could not match 'Foo<K<template-parameter-0-0>>' against 'int'}} \
- // expected-note {{implicit deduction guide declared as 'template <template <typename> typename TTP> requires __is_deducible(test20::Bar, Foo<K<template-parameter-0-0>>) Bar(Foo<K<template-parameter-0-0>>) -> Foo<K<template-parameter-0-0>>'}}
+using Bar = Foo<K<TTP>>; // expected-note {{candidate template ignored: could not match 'Foo<K<TTP>>' against 'int'}} \
+ // expected-note {{implicit deduction guide declared as 'template <template <typename> typename TTP> requires __is_deducible(test20::Bar, Foo<K<TTP>>) Bar(Foo<K<TTP>>) -> Foo<K<TTP>>'}}
template <class T>
class Container {};
diff --git a/clang/test/SemaTemplate/deduction-guide.cpp b/clang/test/SemaTemplate/deduction-guide.cpp
index 7b9ca4d83b020..043a4ccf56e36 100644
--- a/clang/test/SemaTemplate/deduction-guide.cpp
+++ b/clang/test/SemaTemplate/deduction-guide.cpp
@@ -68,7 +68,7 @@ using BT = B<char, 'x'>;
// CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 0 T
// CHECK: |-NonTypeTemplateParmDecl {{.*}} 'T' depth 0 index 1 V
// CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 2 U
-// CHECK: |-NonTypeTemplateParmDecl {{.*}} 'type-parameter-0-2' depth 0 index 3 W
+// CHECK: |-NonTypeTemplateParmDecl {{.*}} 'U' depth 0 index 3 W
// CHECK: |-CXXDeductionGuideDecl {{.*}} 'auto (X<W, V>) -> B<T, V>'
// CHECK: | `-ParmVarDecl {{.*}} 'X<W, V>'
// CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (X<nullptr, 'x'>) -> B<char, 'x'>'
@@ -81,7 +81,7 @@ using BT = B<char, 'x'>;
// CHECK: |-InjectedClassNameType {{.*}} 'B<T, V>' dependent
// CHECK: `-TemplateSpecializationType {{.*}} 'X<W, V>' dependent
// CHECK: |-TemplateArgument expr
-// CHECK: | `-DeclRefExpr {{.*}} 'type-parameter-0-2' NonTypeTemplateParm {{.*}} 'W' 'type-parameter-0-2'
+// CHECK: | `-DeclRefExpr {{.*}} 'U' NonTypeTemplateParm {{.*}} 'W' 'U'
// CHECK: `-TemplateArgument expr
// CHECK: `-DeclRefExpr {{.*}} 'T' NonTypeTemplateParm {{.*}} 'V' 'T'
@@ -99,13 +99,13 @@ using CT = C<int>;
// CHECK: | |-TemplateTypeParmDecl {{.*}} typename depth 1 index 0 X
// CHECK: | `-NonTypeTemplateParmDecl {{.*}} 'X' depth 1 index 1
// CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 2 U
-// CHECK: |-NonTypeTemplateParmDecl {{.*}} 'type-parameter-0-2' depth 0 index 3 V
+// CHECK: |-NonTypeTemplateParmDecl {{.*}} 'U' depth 0 index 3 V
// CHECK: | `-TemplateArgument {{.*}} expr
// CHECK: | `-IntegerLiteral {{.*}} 'int' 0
-// CHECK: |-CXXDeductionGuideDecl {{.*}} 'auto (A, Y<template-parameter-0-1>, type-parameter-0-2) -> C<A>'
+// CHECK: |-CXXDeductionGuideDecl {{.*}} 'auto (A, Y<T>, U) -> C<A>'
// CHECK: | |-ParmVarDecl {{.*}} 'A'
-// CHECK: | |-ParmVarDecl {{.*}} 'Y<template-parameter-0-1>'
-// CHECK: | `-ParmVarDecl {{.*}} 'type-parameter-0-2'
+// CHECK: | |-ParmVarDecl {{.*}} 'Y<T>'
+// CHECK: | `-ParmVarDecl {{.*}} 'U'
// CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (int, Y<B>, int) -> C<int>'
// CHECK: |-TemplateArgument type 'int'
// CHECK: |-TemplateArgument template 'B'
@@ -114,20 +114,20 @@ using CT = C<int>;
// CHECK...
[truncated]
|
hokein
reviewed
Jul 22, 2024
There was a problem hiding this comment.
Thanks, the diagnostics in the test look much better.
There is an ambiguous case that I'm a little concerned about: if the alias template parameter and the underlying template parameter have the same name, the synthesized deduction guide may end up with two template parameters with the same name. For instance, see this example. In such cases, we cannot distinguish between the T1 parameters from the function signature auto (T1, T1) -> X<T1, double>.
However, the diagnostic improvement looks promising, and this seems like the right tradeoff.
hokein
approved these changes
Jul 22, 2024
|
Thanks for the prompt review.
Yeah, this is indeed an interesting case. I played it a bit and realized we would now dump a confusing diagnostic for it: template <class T, class U>
struct X {
X(T, U);
};
template <class T, class T1>
X(T, T1) -> X<T, double>;
template <class T1>
using AX = X<T1, double>;
AX s(1);would result in The printed template parameter list is actually syntactically illegal simply because we merely dump the synthesized parameter list, which actually reuses the written parameter names. I think a solution would be, if we realize there's a name clash when building up a list, we make up and use a different parameter name. (This can be left as a follow-up because I feel we're less likely to run into this case.) Regarding the disambiguation, we could already do that through an AST dump. For the case above, I ran an AST dump locally and got the following: Note that we can see the |
|
FYI this change broke a test that wasn't actually running, I made the test run but disabled the broken case here #99907 |
yuxuanchen1997
pushed a commit
that referenced
this pull request
Jul 25, 2024
… CTAD guides (#99840) This seems to be low-hanging fruit: We could remove all calls to `Context.getCanonicalTemplateArgument()` and gain a better diagnostic/AST. The non-canonical template arguments shouldn't make a difference when synthesizing a CTAD guide, so this is intended to be an NFC. Closes #79798
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This seems to be low-hanging fruit: We could remove all calls to
Context.getCanonicalTemplateArgument()and gain a better diagnostic/AST.The non-canonical template arguments shouldn't make a difference when synthesizing a CTAD guide, so this is intended to be an NFC.
Closes #79798