C++11 constexpr: Add note stacks containing backtraces if constant evaluation

fails within a call to a constexpr function. Add -fconstexpr-backtrace-limit
argument to driver and frontend, to control the maximum number of notes so
produced (default 10). Fix APValue printing to be able to pretty-print all
APValue types, and move the testing for this functionality from a unittest to
a -verify test now that it's visible in clang's output.

llvm-svn: 146749

1 files changed, 9 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 797147e5..3ad555b 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -354,6 +354,11 @@ static void DiagnosticOptsToArgs(const DiagnosticOptions &Opts,
     Res.push_back("-ftemplate-backtrace-limit");
     Res.push_back(llvm::utostr(Opts.TemplateBacktraceLimit));
   }
+  if (Opts.ConstexprBacktraceLimit
+                        != DiagnosticOptions::DefaultConstexprBacktraceLimit) {
+    Res.push_back("-fconstexpr-backtrace-limit");
+    Res.push_back(llvm::utostr(Opts.ConstexprBacktraceLimit));
+  }
 
   if (Opts.TabStop != DiagnosticOptions::DefaultTabStop) {
     Res.push_back("-ftabstop");
@@ -1229,6 +1234,10 @@ static void ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
     = Args.getLastArgIntValue(OPT_ftemplate_backtrace_limit,
                          DiagnosticOptions::DefaultTemplateBacktraceLimit,
                          Diags);
+  Opts.ConstexprBacktraceLimit
+    = Args.getLastArgIntValue(OPT_fconstexpr_backtrace_limit,
+                         DiagnosticOptions::DefaultConstexprBacktraceLimit,
+                         Diags);
   Opts.TabStop = Args.getLastArgIntValue(OPT_ftabstop,
                                     DiagnosticOptions::DefaultTabStop, Diags);
   if (Opts.TabStop == 0 || Opts.TabStop > DiagnosticOptions::MaxTabStop) {