[clang][Interp] Only lazily visit constant globals

[tbaeder]

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[tbaeder]

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[tbaeder]

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[tbaeder]

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[tbaeder]

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[aaron.ballman]

LGTM, I suspect this may have to change for constexpr support in C23, but we can burn that bridge when we get to it.

clang/lib/AST/Interp/ByteCodeExprGen.cpp

if (IsPtr)
       return this->emitGetThisFieldPtr(Offset, E);
     return this->emitGetPtrThisField(Offset, E);
   }
 
   // Lazily visit global declarations we haven't seen yet.
   // This happens in C.
   if (!Ctx.getLangOpts().CPlusPlus) {
     if (const auto *VD = dyn_cast<VarDecl>(D);
-        VD && VD->hasGlobalStorage() && VD->getAnyInitializer()) {
+        VD && VD->hasGlobalStorage() && VD->getAnyInitializer() &&
+        VD->getType().isConstQualified()) {
       if (!this->visitVarDecl(VD))
         return false;
       // Retry.
       return this->VisitDeclRefExpr(E);
     }
   }
 
   return this->emitInvalidDeclRef(E, E);

clang/test/AST/Interp/c.c

 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -pedantic -verify=pedantic-expected %s
 // RUN: %clang_cc1 -verify=ref %s
 // RUN: %clang_cc1 -pedantic -verify=pedantic-ref %s
 
 _Static_assert(1, "");
 _Static_assert(0 != 1, "");
 _Static_assert(1.0 == 1.0, ""); // pedantic-ref-warning {{not an integer constant expression}} \
                                 // pedantic-expected-warning {{not an integer constant expression}}
 _Static_assert(1 && 1.0, ""); // pedantic-ref-warning {{not an integer constant expression}} \
                               // pedantic-expected-warning {{not an integer constant expression}}
 _Static_assert( (5 > 4) + (3 > 2) == 2, "");
 _Static_assert(!!1.0, ""); // pedantic-ref-warning {{not an integer constant expression}} \
                            // pedantic-expected-warning {{not an integer constant expression}}
 _Static_assert(!!1, "");
 
-/// FIXME: Should also be rejected in the new interpreter
-int a = (1 == 1 ? 5 : 3);
+int a = (1 == 1 ? 5 : 3); // expected-note {{declared here}} \
+                          // pedantic-expected-note {{declared here}}
 _Static_assert(a == 5, ""); // ref-error {{not an integral constant expression}} \
                             // pedantic-ref-error {{not an integral constant expression}} \
-                            // pedantic-expected-warning {{not an integer constant expression}}
+                            // expected-error {{not an integral constant expression}} \
+                            // expected-note {{read of non-const variable}} \
+                            // pedantic-expected-error {{not an integral constant expression}} \
+                            // pedantic-expected-note {{read of non-const variable}}
+
 
 const int b = 3;
 _Static_assert(b == 3, ""); // pedantic-ref-warning {{not an integer constant expression}} \
                             // pedantic-expected-warning {{not an integer constant expression}}
 
 const int c; // ref-note {{declared here}} \
              // pedantic-ref-note {{declared here}} \
              // expected-note {{declared here}} \