From 775b5c1d5db1add584a637c301b973babb3ca05f Mon Sep 17 00:00:00 2001
From: Yichao Yu <yyc1992@gmail.com>
Date: Mon, 7 Sep 2020 02:06:55 -0400
Subject: [PATCH] Fix `getfield_tfunc` for constant `TypeName`

The field should be either `Symbol` or `Int`. Ref #37423

Unlike #37423, in additional to worse type info in inference,
the missing type check here can actually cause type inference error
due to errors in user code.
---
 base/compiler/tfuncs.jl    |  8 +++++++-
 test/compiler/inference.jl | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/base/compiler/tfuncs.jl b/base/compiler/tfuncs.jl
index 9ab8f56d31392..6528de5bade23 100644
--- a/base/compiler/tfuncs.jl
+++ b/base/compiler/tfuncs.jl
@@ -761,7 +761,13 @@ function getfield_tfunc(@nospecialize(s00), @nospecialize(name))
                     t === nothing || return t
                 end
             elseif isa(sv, Core.TypeName)
-                fld = isa(nv, Symbol) ? fieldindex(Core.TypeName, nv, false) : nv
+                fld = if isa(nv, Symbol)
+                    fieldindex(Core.TypeName, nv, false)
+                elseif isa(nv, Int)
+                    nv
+                else
+                    return Bottom
+                end
                 if (fld == TYPENAME_NAME_FIELDINDEX ||
                     fld == TYPENAME_MODULE_FIELDINDEX ||
                     fld == TYPENAME_WRAPPER_FIELDINDEX)
diff --git a/test/compiler/inference.jl b/test/compiler/inference.jl
index 6ed0a4011b0b3..7f0c5fe2c90a2 100644
--- a/test/compiler/inference.jl
+++ b/test/compiler/inference.jl
@@ -2751,3 +2751,23 @@ f_generator_splat(t::Tuple) = tuple((identity(l) for l in t)...)
 @test !Core.Compiler.sizeof_nothrow(UnionAll)
 
 @test Base.return_types(Expr) == Any[Expr]
+
+# Use a global constant to rely less on unrelated constant propagation
+const const_int32_typename = Int32.name
+getfield_const_typename_good1() = getfield(const_int32_typename, 1)
+getfield_const_typename_good2() = getfield(const_int32_typename, :name)
+getfield_const_typename_bad1() = getfield(const_int32_typename, 0x1)
+@eval getfield_const_typename_bad2() = getfield(const_int32_typename, $(()))
+let goodf, badf
+    for goodf in [getfield_const_typename_good1, getfield_const_typename_good2]
+        local code = code_typed(goodf, Tuple{})[1].first.code
+        @test code[1] === Core.ReturnNode(QuoteNode(:Int32))
+        @test goodf() === :Int32
+    end
+    for badf in [getfield_const_typename_bad1, getfield_const_typename_bad2]
+        local code = code_typed(badf, Tuple{})[1].first.code
+        @test Meta.isexpr(code[1], :call)
+        @test code[end] === Core.ReturnNode()
+        @test_throws TypeError badf()
+    end
+end