[clang] fix code synthesis context depth limit logic #161103
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This makes the instantation depth limit be checked whenever the code synthesis context is pushed, not only when creating a InstantiatingTemplate RAII object. Also fix the note suggesting the user increases `-ftemplate-depth` so it is printed even in a SFINAE context.
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@llvm/pr-subscribers-clang Author: Matheus Izvekov (mizvekov) ChangesThis makes the instantation depth limit be checked whenever the code synthesis context is pushed, not only when creating a InstantiatingTemplate RAII object. Also fix the note suggesting the user increases Full diff: https://github.com/llvm/llvm-project/pull/161103.diff 6 Files Affected:
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index dc4c6d3de27c1..fa202fba29370 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -5770,8 +5770,10 @@ def err_template_recursion_depth_exceeded : Error<
def err_constraint_depends_on_self
: Error<"satisfaction of constraint %0 depends on itself">,
NoSFINAE;
-def note_template_recursion_depth : Note<
- "use -ftemplate-depth=N to increase recursive template instantiation depth">;
+def note_template_recursion_depth
+ : Note<"use -ftemplate-depth=N to increase recursive template "
+ "instantiation depth">,
+ NoSFINAE;
def err_template_instantiate_within_definition : Error<
"%select{implicit|explicit}0 instantiation of template %1 within its"
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 2bd6be2a32cd5..f53aafdeb4f36 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -13335,8 +13335,6 @@ class Sema final : public SemaBase {
Sema &SemaRef;
bool Invalid;
bool AlreadyInstantiating;
- bool CheckInstantiationDepth(SourceLocation PointOfInstantiation,
- SourceRange InstantiationRange);
InstantiatingTemplate(Sema &SemaRef,
CodeSynthesisContext::SynthesisKind Kind,
@@ -13529,7 +13527,7 @@ class Sema final : public SemaBase {
~ArgPackSubstIndexRAII() { Self.ArgPackSubstIndex = OldSubstIndex; }
};
- void pushCodeSynthesisContext(CodeSynthesisContext Ctx);
+ bool pushCodeSynthesisContext(CodeSynthesisContext Ctx);
void popCodeSynthesisContext();
void PrintContextStack(InstantiationContextDiagFuncRef DiagFunc) {
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 1ff94d7ae397f..f1c9c5c868159 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -616,29 +616,30 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
Invalid = true;
return;
}
- Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
+
+ CodeSynthesisContext Inst;
+ Inst.Kind = Kind;
+ Inst.PointOfInstantiation = PointOfInstantiation;
+ Inst.Entity = Entity;
+ Inst.Template = Template;
+ Inst.TemplateArgs = TemplateArgs.data();
+ Inst.NumTemplateArgs = TemplateArgs.size();
+ Inst.DeductionInfo = DeductionInfo;
+ Inst.InstantiationRange = InstantiationRange;
+ Inst.InConstraintSubstitution =
+ Inst.Kind == CodeSynthesisContext::ConstraintSubstitution;
+ if (!SemaRef.CodeSynthesisContexts.empty())
+ Inst.InConstraintSubstitution |=
+ SemaRef.CodeSynthesisContexts.back().InConstraintSubstitution;
+
+ Invalid = SemaRef.pushCodeSynthesisContext(Inst);
if (!Invalid) {
- CodeSynthesisContext Inst;
- Inst.Kind = Kind;
- Inst.PointOfInstantiation = PointOfInstantiation;
- Inst.Entity = Entity;
- Inst.Template = Template;
- Inst.TemplateArgs = TemplateArgs.data();
- Inst.NumTemplateArgs = TemplateArgs.size();
- Inst.DeductionInfo = DeductionInfo;
- Inst.InstantiationRange = InstantiationRange;
- Inst.InConstraintSubstitution =
- Inst.Kind == CodeSynthesisContext::ConstraintSubstitution;
- if (!SemaRef.CodeSynthesisContexts.empty())
- Inst.InConstraintSubstitution |=
- SemaRef.CodeSynthesisContexts.back().InConstraintSubstitution;
-
- SemaRef.pushCodeSynthesisContext(Inst);
-
- AlreadyInstantiating = !Inst.Entity ? false :
- !SemaRef.InstantiatingSpecializations
- .insert({Inst.Entity->getCanonicalDecl(), Inst.Kind})
- .second;
+ AlreadyInstantiating =
+ !Inst.Entity
+ ? false
+ : !SemaRef.InstantiatingSpecializations
+ .insert({Inst.Entity->getCanonicalDecl(), Inst.Kind})
+ .second;
atTemplateBegin(SemaRef.TemplateInstCallbacks, SemaRef, Inst);
}
}
@@ -834,18 +835,34 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
: InstantiatingTemplate(SemaRef, CodeSynthesisContext::PartialOrderingTTP,
ArgLoc, InstantiationRange, PArg) {}
-void Sema::pushCodeSynthesisContext(CodeSynthesisContext Ctx) {
+bool Sema::pushCodeSynthesisContext(CodeSynthesisContext Ctx) {
Ctx.SavedInNonInstantiationSFINAEContext = InNonInstantiationSFINAEContext;
InNonInstantiationSFINAEContext = false;
- CodeSynthesisContexts.push_back(Ctx);
-
- if (!Ctx.isInstantiationRecord())
+ if (!Ctx.isInstantiationRecord()) {
++NonInstantiationEntries;
+ } else {
+ assert(SemaRef.NonInstantiationEntries <=
+ SemaRef.CodeSynthesisContexts.size());
+ if ((SemaRef.CodeSynthesisContexts.size() -
+ SemaRef.NonInstantiationEntries) >
+ SemaRef.getLangOpts().InstantiationDepth) {
+ SemaRef.Diag(Ctx.PointOfInstantiation,
+ diag::err_template_recursion_depth_exceeded)
+ << SemaRef.getLangOpts().InstantiationDepth << Ctx.InstantiationRange;
+ SemaRef.Diag(Ctx.PointOfInstantiation,
+ diag::note_template_recursion_depth)
+ << SemaRef.getLangOpts().InstantiationDepth;
+ return true;
+ }
+ }
+
+ CodeSynthesisContexts.push_back(Ctx);
// Check to see if we're low on stack space. We can't do anything about this
// from here, but we can at least warn the user.
StackHandler.warnOnStackNearlyExhausted(Ctx.PointOfInstantiation);
+ return false;
}
void Sema::popCodeSynthesisContext() {
@@ -907,25 +924,6 @@ static std::string convertCallArgsToString(Sema &S,
return Result;
}
-bool Sema::InstantiatingTemplate::CheckInstantiationDepth(
- SourceLocation PointOfInstantiation,
- SourceRange InstantiationRange) {
- assert(SemaRef.NonInstantiationEntries <=
- SemaRef.CodeSynthesisContexts.size());
- if ((SemaRef.CodeSynthesisContexts.size() -
- SemaRef.NonInstantiationEntries)
- <= SemaRef.getLangOpts().InstantiationDepth)
- return false;
-
- SemaRef.Diag(PointOfInstantiation,
- diag::err_template_recursion_depth_exceeded)
- << SemaRef.getLangOpts().InstantiationDepth
- << InstantiationRange;
- SemaRef.Diag(PointOfInstantiation, diag::note_template_recursion_depth)
- << SemaRef.getLangOpts().InstantiationDepth;
- return true;
-}
-
void Sema::PrintInstantiationStack(InstantiationContextDiagFuncRef DiagFunc) {
// Determine which template instantiations to skip, if any.
unsigned SkipStart = CodeSynthesisContexts.size(), SkipEnd = SkipStart;
diff --git a/clang/test/SemaCXX/invalid-requirement-requires-expr.cpp b/clang/test/SemaCXX/invalid-requirement-requires-expr.cpp
index 097ada3caa135..436dfb9aac0a7 100644
--- a/clang/test/SemaCXX/invalid-requirement-requires-expr.cpp
+++ b/clang/test/SemaCXX/invalid-requirement-requires-expr.cpp
@@ -17,8 +17,7 @@ constexpr bool A<x>::far() {
b.data_member;
requires A<x-1>::far(); // #Invalid
// expected-error@#Invalid {{recursive template instantiation exceeded maximum depth}}
- // expected-note@#Invalid {{in instantiation}}
- // expected-note@#Invalid 2 {{while}}
+ // expected-note@#Invalid 3 {{while}}
// expected-note@#Invalid {{contexts in backtrace}}
// expected-note@#Invalid {{increase recursive template instantiation depth}}
};
diff --git a/clang/test/SemaTemplate/instantiation-depth-subst-2.cpp b/clang/test/SemaTemplate/instantiation-depth-subst-2.cpp
index 2b519e974a907..66fd1af0d1429 100644
--- a/clang/test/SemaTemplate/instantiation-depth-subst-2.cpp
+++ b/clang/test/SemaTemplate/instantiation-depth-subst-2.cpp
@@ -2,5 +2,6 @@
template<int N> struct S { };
template<typename T> S<T() + T()> operator+(T, T); // expected-error {{instantiation exceeded maximum depth}} expected-note 2{{while substituting}}
+// expected-note@-1 {{use -ftemplate-depth=N to increase recursive template instantiation depth}}
S<0> s;
int k = s + s; // expected-note {{while substituting}}
diff --git a/clang/test/SemaTemplate/instantiation-depth-subst.cpp b/clang/test/SemaTemplate/instantiation-depth-subst.cpp
index 062a8ed08bb64..17944bc3aaa40 100644
--- a/clang/test/SemaTemplate/instantiation-depth-subst.cpp
+++ b/clang/test/SemaTemplate/instantiation-depth-subst.cpp
@@ -3,7 +3,8 @@
// PR9793
template<typename T> auto f(T t) -> decltype(f(t)); // \
// expected-error {{recursive template instantiation exceeded maximum depth of 2}} \
-// expected-note 2 {{while substituting}}
+// expected-note 2 {{while substituting}} \
+// expected-note {{use -ftemplate-depth=N to increase recursive template instantiation depth}}
struct S {};
int k = f(S{}); // expected-note {{while substituting}}
|
cor3ntin
approved these changes
Sep 29, 2025
mizvekov
deleted the
users/mizvekov/code-synthesis-context-depth-exceeded-fix
branch
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/163/builds/27261 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/27/builds/16727 Here is the relevant piece of the build log for the reference |
erichkeane
reviewed
Sep 29, 2025
| } | ||
| Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange); | ||
|
|
||
| CodeSynthesisContext Inst; |
There was a problem hiding this comment.
This seems in desperate need of a constructor here :)
mahesh-attarde
pushed a commit
to mahesh-attarde/llvm-project
that referenced
this pull request
Oct 3, 2025
This makes the instantation depth limit be checked whenever the code synthesis context is pushed, not only when creating a InstantiatingTemplate RAII object. Also fix the note suggesting the user increases `-ftemplate-depth` so it is printed even in a SFINAE context.
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This makes the instantation depth limit be checked whenever the code synthesis context is pushed, not only when creating a InstantiatingTemplate RAII object.
Also fix the note suggesting the user increases
-ftemplate-depthso it is printed even in a SFINAE context.