[PATCH] D91162: Give up on evaluating value-dependent potential constexpr before hitting the assertion.

[Adam Czachorowski via Phabricator via cfe-commits]

adamcz created this revision.
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This addresses a new type of assert() crash since
f7f2e4261a98b2da519d58e7f6794b013cda7a4b <https://reviews.llvm.org/rGf7f2e4261a98b2da519d58e7f6794b013cda7a4b>.

EvaluateInPlace assumes it's never called on value-dependent expression,
but it is possible for this to happen when inside CallExpr and errors
were encountered earlier.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91162

Files:
  clang/lib/AST/ExprConstant.cpp
  clang/test/SemaCXX/constexpr-value-dependent.cpp


Index: clang/test/SemaCXX/constexpr-value-dependent.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/constexpr-value-dependent.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 %s -std=c++11 -fsyntax-only -verify
+
+template<int x> constexpr int f(int y) {
+  return x * y;
+}
+
+// The error makes the CallExpr become potentially value-dependent. This used to
+// cause a crash.
+constexpr int test(int x) {
+  return f<1>(f<x>(1)); // expected-error {{no matching function for call to 'f'}} expected-note at -7{{candidate template ignored}}
+}
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -5981,6 +5981,9 @@
 static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
                             CallRef Call, EvalInfo &Info,
                             bool NonNull = false) {
+  if (Arg->isValueDependent())
+    return false;
+
   LValue LV;
   // Create the parameter slot and register its destruction. For a vararg
   // argument, create a temporary.


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