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this came up during discussion of other header unit constraints, we had not
implemented it yet.
found a test case where we'd accidentally broken this rule too.
[module.import/6] last sentence:
A header unit shall not contain a definition of a non-inline function or
variable whose name has external linkage.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D140261
Files:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/test/CXX/module/module.import/p6.cpp
clang/test/CodeGenCXX/module-initializer-header.cppm
Index: clang/test/CodeGenCXX/module-initializer-header.cppm
===================================================================
--- clang/test/CodeGenCXX/module-initializer-header.cppm
+++ clang/test/CodeGenCXX/module-initializer-header.cppm
@@ -8,24 +8,24 @@
//
//--- header.h
int foo();
-int i = foo();
+static int i = foo();
//--- M.cppm
module;
import "header.h";
export module M;
-// CHECK: @i = {{.*}}global i32 0
+// CHECK: @_ZL1i = {{.*}}global i32 0
// CHECK: void @__cxx_global_var_init()
// CHECK-NEXT: entry:
// CHECK-NEXT: %call = call noundef{{.*}} i32 @_Z3foov()
-// CHECK-NEXT: store i32 %call, ptr @i
+// CHECK-NEXT: store i32 %call, ptr @_ZL1i
//--- Use.cpp
import "header.h";
-// CHECK: @i = {{.*}}global i32 0
+// CHECK: @_ZL1i = {{.*}}global i32 0
// CHECK: void @__cxx_global_var_init()
// CHECK-NEXT: entry:
// CHECK-NEXT: %call = call noundef{{.*}} i32 @_Z3foov()
-// CHECK-NEXT: store i32 %call, ptr @i
+// CHECK-NEXT: store i32 %call, ptr @_ZL1i
Index: clang/test/CXX/module/module.import/p6.cpp
===================================================================
--- /dev/null
+++ clang/test/CXX/module/module.import/p6.cpp
@@ -0,0 +1,24 @@
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cc1 -std=c++20 -x c++-header %t/bad-header-unit.h \
+// RUN: -emit-header-unit -o %t/bad-header-unit.pcm -verify
+
+//--- bad-header-unit.h
+
+inline int ok_foo () { return 0;}
+
+static int ok_bar ();
+
+int ok_decl ();
+
+int bad_def () { return 2;} // expected-error {{non-inline external definitions are not permitted in C++ header units}}
+
+inline int ok_inline_var = 1;
+
+static int ok_static_var;
+
+int ok_var_decl;
+
+int bad_var_definition = 3; // expected-error {{non-inline external definitions are not permitted in C++ header units}}
+
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -12952,6 +12952,17 @@
VDecl->setInvalidDecl();
}
+ // C++ [module.import/6] external definitions are not permitted in header
+ // units.
+ if (getLangOpts().CPlusPlus20 && getLangOpts().CPlusPlusModules &&
+ !ModuleScopes.empty() && ModuleScopes.back().Module->isHeaderUnit()) {
+ if (VDecl->getFormalLinkage() == Linkage::ExternalLinkage &&
+ !VDecl->isInline()) {
+ Diag(VDecl->getLocation(), diag::err_extern_def_in_header_unit);
+ VDecl->setInvalidDecl();
+ }
+ }
+
// If adding the initializer will turn this declaration into a definition,
// and we already have a definition for this variable, diagnose or otherwise
// handle the situation.
@@ -15100,6 +15111,17 @@
}
}
+ // C++ [module.import/6] external definitions are not permitted in header
+ // units.
+ if (getLangOpts().CPlusPlus20 && getLangOpts().CPlusPlusModules &&
+ !ModuleScopes.empty() && ModuleScopes.back().Module->isHeaderUnit()) {
+ if (FD->getFormalLinkage() == Linkage::ExternalLinkage &&
+ !FD->isInlined()) {
+ Diag(FD->getLocation(), diag::err_extern_def_in_header_unit);
+ FD->setInvalidDecl();
+ }
+ }
+
// Ensure that the function's exception specification is instantiated.
if (const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>())
ResolveExceptionSpec(D->getLocation(), FPT);
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -11233,6 +11233,8 @@
"add 'export' here if this is intended to be a module interface unit">;
def err_invalid_module_name : Error<
"%0 is %select{an invalid|a reserved}1 name for a module">;
+def err_extern_def_in_header_unit : Error<
+ "non-inline external definitions are not permitted in C++ header units">;
def ext_equivalent_internal_linkage_decl_in_modules : ExtWarn<
"ambiguous use of internal linkage declaration %0 defined in multiple modules">,
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