Reland r348741 "[Sema] Further improvements to to static_assert diagnostics."
Fix a dangling reference to temporary, never return nullptr.
llvm-svn: 348834
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 56302d6..a3dbb44 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -3052,30 +3052,42 @@
return Cond;
}
-// Print a diagnostic for the failing static_assert expression. Defaults to
-// pretty-printing the expression.
-static void prettyPrintFailedBooleanCondition(llvm::raw_string_ostream &OS,
- const Expr *FailedCond,
- const PrintingPolicy &Policy) {
- const auto *DR = dyn_cast<DeclRefExpr>(FailedCond);
- if (DR && DR->getQualifier()) {
- // If this is a qualified name, expand the template arguments in nested
- // qualifiers.
- DR->getQualifier()->print(OS, Policy, true);
- // Then print the decl itself.
- const ValueDecl *VD = DR->getDecl();
- OS << VD->getName();
- if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
- // This is a template variable, print the expanded template arguments.
- printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
+namespace {
+
+// A PrinterHelper that prints more helpful diagnostics for some sub-expressions
+// within failing boolean expression, such as substituting template parameters
+// for actual types.
+class FailedBooleanConditionPrinterHelper : public PrinterHelper {
+public:
+ explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
+ : Policy(P) {}
+
+ bool handledStmt(Stmt *E, raw_ostream &OS) override {
+ const auto *DR = dyn_cast<DeclRefExpr>(E);
+ if (DR && DR->getQualifier()) {
+ // If this is a qualified name, expand the template arguments in nested
+ // qualifiers.
+ DR->getQualifier()->print(OS, Policy, true);
+ // Then print the decl itself.
+ const ValueDecl *VD = DR->getDecl();
+ OS << VD->getName();
+ if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
+ // This is a template variable, print the expanded template arguments.
+ printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
+ }
+ return true;
}
- return;
+ return false;
}
- FailedCond->printPretty(OS, nullptr, Policy);
-}
+
+private:
+ const PrintingPolicy Policy;
+};
+
+} // end anonymous namespace
std::pair<Expr *, std::string>
-Sema::findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond) {
+Sema::findFailedBooleanCondition(Expr *Cond) {
Cond = lookThroughRangesV3Condition(PP, Cond);
// Separate out all of the terms in a conjunction.
@@ -3104,18 +3116,14 @@
break;
}
}
-
- if (!FailedCond) {
- if (!AllowTopLevelCond)
- return { nullptr, "" };
-
+ if (!FailedCond)
FailedCond = Cond->IgnoreParenImpCasts();
- }
std::string Description;
{
llvm::raw_string_ostream Out(Description);
- prettyPrintFailedBooleanCondition(Out, FailedCond, getPrintingPolicy());
+ FailedBooleanConditionPrinterHelper Helper(getPrintingPolicy());
+ FailedCond->printPretty(Out, &Helper, getPrintingPolicy());
}
return { FailedCond, Description };
}
@@ -3199,9 +3207,7 @@
Expr *FailedCond;
std::string FailedDescription;
std::tie(FailedCond, FailedDescription) =
- findFailedBooleanCondition(
- TemplateArgs[0].getSourceExpression(),
- /*AllowTopLevelCond=*/true);
+ findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
// Remove the old SFINAE diagnostic.
PartialDiagnosticAt OldDiag =
@@ -9649,7 +9655,7 @@
Expr *FailedCond;
std::string FailedDescription;
std::tie(FailedCond, FailedDescription) =
- findFailedBooleanCondition(Cond, /*AllowTopLevelCond=*/true);
+ findFailedBooleanCondition(Cond);
Diag(FailedCond->getExprLoc(),
diag::err_typename_nested_not_found_requirement)