Change default visibility of interface members and update docs. (#3381)

* Update behavior around interfaces and docs.

* Update toc

---------

Co-authored-by: Yong He <yhe@nvidia.com>

6 files changed, 46 insertions, 8 deletions

diff --git a/source/slang/slang-ast-support-types.h b/source/slang/slang-ast-support-types.h
index 1e71d0c4a..f771e24b6 100644
--- a/source/slang/slang-ast-support-types.h
+++ b/source/slang/slang-ast-support-types.h
@@ -66,6 +66,17 @@ namespace Slang
     void printDiagnosticArg(StringBuilder& sb, Val* val);
     void printDiagnosticArg(StringBuilder& sb, DeclRefBase* declRefBase);
 
+    struct QualifiedDeclPath
+    {
+        DeclRefBase* declRef;
+        QualifiedDeclPath() = default;
+        QualifiedDeclPath(DeclRefBase* declRef)
+            : declRef(declRef)
+        {}
+    };
+    // Prints the fully qualified decl name.
+    void printDiagnosticArg(StringBuilder& sb, QualifiedDeclPath path);
+
 
     class SyntaxNode;
     SourceLoc getDiagnosticPos(SyntaxNode const* syntax);
@@ -1605,6 +1616,7 @@ namespace Slang
         Public,
         Default = Internal,
     };
+
 } // namespace Slang
 
 #endif
diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 671bb26dd..39f0b9096 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -4059,7 +4059,19 @@ namespace Slang
                 continue;
 
             if (doesMemberSatisfyRequirement(member.declRef, requiredMemberDeclRef, witnessTable))
+            {
+                // The member satisfies the requirement in every other way except that
+                // it may have a lower visibility than min(parentVisibility, requirementVisibilty),
+                // in that case we will treat it as an error.
+                auto minRequiredVisibility = Math::Min(getDeclVisibility(requiredMemberDeclRef.getDecl()), getTypeVisibility(subType));
+                if (getDeclVisibility(member.declRef.getDecl()) < minRequiredVisibility)
+                {
+                    getSink()->diagnose(member.declRef, Diagnostics::satisfyingDeclCannotHaveLowerVisibility, member.declRef);
+                    getSink()->diagnose(requiredMemberDeclRef, Diagnostics::seeDeclarationOf, QualifiedDeclPath(requiredMemberDeclRef));
+                    return false;
+                }
                 return true;
+            }
         }
 
         // If we reach this point then there were no members suitable
diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index dd868f70c..9d1898cf5 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -841,6 +841,12 @@ namespace Slang
             else if (as<PrivateModifier>(modifier))
                 return DeclVisibility::Private;
         }
+        
+        // Interface members will always have the same visibility as the interface itself.
+        if (auto interfaceDecl = findParentInterfaceDecl(decl))
+        {
+            return getDeclVisibility(interfaceDecl);
+        }
 
         if (auto parentModule = getModuleDecl(decl))
             return parentModule->isInLegacyLanguage ? DeclVisibility::Public : DeclVisibility::Internal;
@@ -919,6 +925,13 @@ namespace Slang
         {
             getSink()->diagnose(loc, Diagnostics::declIsNotVisible, lookupResult.item.declRef);
             outDiagnosed = true;
+
+            if (getShared()->isInLanguageServer())
+            {
+                // When in language server mode, return the unfiltered result so we can still
+                // provide language service around it.
+                return lookupResult;
+            }
         }
         return result;
     }
diff --git a/source/slang/slang-diagnostic-defs.h b/source/slang/slang-diagnostic-defs.h
index c95d5ea98..ac3220f4b 100644
--- a/source/slang/slang-diagnostic-defs.h
+++ b/source/slang/slang-diagnostic-defs.h
@@ -360,7 +360,7 @@ DIAGNOSTIC(30505, Error, implementingMustReferencePrimaryModuleFile, "the source
 // Visibilty
 DIAGNOSTIC(30600, Error, declIsNotVisible, "'$0' is not accessible from the current context.")
 DIAGNOSTIC(30601, Error, declCannotHaveHigherVisibility, "'$0' cannot have a higher visibility than '$1'.")
-DIAGNOSTIC(30602, Error, declCannotHaveLowerVisibility, "'$0' cannot have a lower visibility than '$1'.")
+DIAGNOSTIC(30602, Error, satisfyingDeclCannotHaveLowerVisibility, "'$0' is less visible than the interface requirement it satisfies.")
 DIAGNOSTIC(30603, Error, invalidUseOfPrivateVisibility, "'$0' cannot have private visibility.")
 DIAGNOSTIC(30604, Error, useOfLessVisibleType, "'$0' references less visible type '$1'.")
 
diff --git a/source/slang/slang-syntax.cpp b/source/slang/slang-syntax.cpp
index 678d9ec26..6350a7e4d 100644
--- a/source/slang/slang-syntax.cpp
+++ b/source/slang/slang-syntax.cpp
@@ -2,7 +2,7 @@
 
 #include "slang-compiler.h"
 #include "slang-visitor.h"
-
+#include "slang-ast-print.h"
 #include <typeinfo>
 #include <assert.h>
 
@@ -55,6 +55,13 @@ void printDiagnosticArg(StringBuilder& sb, QualType const& type)
         sb << "<null>";
 }
 
+void printDiagnosticArg(StringBuilder& sb, QualifiedDeclPath path)
+{
+    ASTPrinter printer(getCurrentASTBuilder());
+    printer.addDeclPath(path.declRef);
+    sb << printer.getString();
+}
+
 SourceLoc getDiagnosticPos(SyntaxNode const* syntax)
 {
     if (!syntax)
diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 0f53ffcd5..2852dd43e 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -1117,12 +1117,6 @@ SLANG_NO_THROW slang::IModule* SLANG_MCALL Linkage::loadModuleFromSource(
             if (SLANG_SUCCEEDED(Path::getCanonical(pathStr, cannonicalPath)))
             {
                 pathInfo = PathInfo::makeNormal(pathStr, cannonicalPath);
-                ComPtr<ISlangBlob> uniqueIdentity;
-                getFileSystemExt()->getFileUniqueIdentity(cannonicalPath.getBuffer(), uniqueIdentity.writeRef());
-                if (uniqueIdentity && uniqueIdentity->getBufferSize() != 0)
-                {
-                    pathInfo.uniqueIdentity = (char*)uniqueIdentity->getBufferPointer();
-                }
             }
         }
         auto module = loadModule(