[Compile Time Values] Emit diagnostic note with parameter location on a non-@const argument to a @const parameter

Author: artemcm

include/swift/AST/DiagnosticsCommon.def

@@ -90,7 +90,7 @@ ERROR(require_const_initializer_for_const,none,
       "@const value should be initialized with a compile-time value", ())
 
 ERROR(require_const_arg_for_parameter,none,
-      "expected a compile-time value for a '@const' parameter", ())
+      "expected a compile-time value argument for a '@const' parameter", ())
 
 // FIXME: Used by both the parser and the type-checker.
 ERROR(func_decl_without_brace,PointsToFirstBadToken,

lib/SILOptimizer/Mandatory/DiagnoseUnknownCompileTimeValues.cpp

@@ -176,7 +176,8 @@ class DiagnoseUnknownCompileTimeValues : public SILModuleTransform {
 
   void verifyLocal(DebugValueInst *DBI) {
     auto Decl = DBI->getDecl();
-    if (!Decl || !isa<VarDecl>(Decl) || isa<ParamDecl>(Decl) || !Decl->isConstVal())
+    if (!Decl || !isa<VarDecl>(Decl) || isa<ParamDecl>(Decl) ||
+        !Decl->isConstVal())
       return;
 
     auto Value = ConstExprState.getConstantValue(DBI->getOperand());
@@ -228,14 +229,16 @@ class DiagnoseUnknownCompileTimeValues : public SILModuleTransform {
 
     if (hasConst) {
       for (size_t i = 0; i < CalleeParameters->size(); ++i) {
-        auto CorrespondingArg = ApplyArgRefs[i];
-        if (CalleeParameters->get(i)->isConstVal()) {
+        const auto &CorrespondingArg = ApplyArgRefs[i];
+        const auto &CorrespondingParameter = CalleeParameters->get(i);
+        if (CorrespondingParameter->isConstVal()) {
           LLVM_DEBUG({
-            llvm::dbgs() << "Argument of fn{" << CalleeDecl->getNameStr() << "} ";
-            llvm::dbgs() << CalleeParameters->get(i)->getNameStr() << ": ";
+            llvm::dbgs() << "Argument of fn{" << CalleeDecl->getNameStr()
+                         << "} ";
+            llvm::dbgs() << CorrespondingParameter->getNameStr() << ": ";
             std::string typeName;
             llvm::raw_string_ostream out(typeName);
-            CalleeParameters->get(i)->getTypeRepr()->print(out);
+            CorrespondingParameter->getTypeRepr()->print(out);
             auto Value = ConstExprState.getConstantValue(CorrespondingArg);
             llvm::dbgs() << typeName << " = ";
             printSymbolicValueValue(Value, Allocator);
@@ -248,6 +251,10 @@ class DiagnoseUnknownCompileTimeValues : public SILModuleTransform {
               ArgLocation = ApplyExprNode->getArgs()[i].getLoc();
             getModule()->getASTContext().Diags.diagnose(
                 ArgLocation, diag::require_const_arg_for_parameter);
+            getModule()->getASTContext().Diags.diagnose(
+                CorrespondingParameter->getLoc(),
+                diag::kind_declname_declared_here, DescriptiveDeclKind::Param,
+                CorrespondingParameter->getName());
           }
         }
       }

test/ConstValues/IntegerLiterals.swift

@@ -1,6 +1,6 @@
 // Constant globals on simple integer literals
 // REQUIRES: swift_feature_CompileTimeValues
-// RUN: %target-swift-frontend -emit-ir -primary-file %s -parse-as-library -enable-experimental-feature CompileTimeValues
+// RUN: %target-swift-frontend -emit-ir -primary-file %s -parse-as-library -verify -enable-experimental-feature CompileTimeValues
 
 @const let constGlobal1: Int = 42
 @const let constGlobal2: UInt = 42

test/ConstValues/Parameters.swift

@@ -0,0 +1,19 @@
+// Constant globals on simple integer literals
+// REQUIRES: swift_feature_CompileTimeValues
+// RUN: %target-swift-frontend -emit-sil -primary-file %s -verify -enable-experimental-feature CompileTimeValues
+
+func bar(@const _ thing: UInt) -> UInt {
+    return thing
+}
+
+func foo() {
+    let _ = bar(42)
+    let _ = bar(0xf000f000)
+    #if _pointerBitWidth(_64)
+    let _ = bar(0xf000f000_f000f000)
+    #endif
+    let _ = bar(UInt.random(in: 0..<10))
+    // expected-error@-1 {{expected a compile-time value argument for a '@const' parameter}}
+    // expected-note@-12 {{parameter 'thing' declared here}}
+}
+