Merge pull request #32674 from JuliaLang/vc/pure

fix propagation of pure and const results

Author: vchuravy

base/compiler/abstractinterpretation.jl

@@ -1147,6 +1147,8 @@ function typeinf_local(frame::InferenceState)
                     # only propagate information we know we can store
                     # and is valid inter-procedurally
                     rt = widenconst(rt)
+                elseif isa(rt, Const) && rt.actual
+                    rt = Const(rt.val)
                 end
                 if tchanged(rt, frame.bestguess)
                     # new (wider) return type for frame

base/compiler/ssair/inlining.jl

@@ -663,7 +663,7 @@ function analyze_method!(idx::Int, sig::Signature, @nospecialize(metharg), meths
     methsig = method.sig
 
     # Check whether this call just evaluates to a constant
-    if isa(f, widenconst(ft)) && !isdefined(method, :generator) && method.pure &&
+    if isa(f, widenconst(ft)) &&
             isa(stmttyp, Const) && stmttyp.actual && is_inlineable_constant(stmttyp.val)
         return ConstantCase(quoted(stmttyp.val), method, Any[methsp...], metharg)
     end

test/compiler/contextual.jl

@@ -62,7 +62,7 @@ module MiniCassette
     end
 
     function overdub_generator(self, c, f, args)
-        if f <: Core.Builtin || !isdefined(f, :instance)
+        if !isdefined(f, :instance)
             return :(return f(args...))
         end
 
@@ -83,6 +83,10 @@ module MiniCassette
         code_info
     end
 
+    @inline function overdub(c::Ctx, f::Union{Core.Builtin, Core.IntrinsicFunction}, args...)
+        f(args...)
+    end
+
     @eval function overdub(c::Ctx, f, args...)
         $(Expr(:meta, :generated_only))
         $(Expr(:meta,
@@ -112,5 +116,20 @@ f() = 2
 # Test that pure propagates for Cassette
 Base.@pure isbitstype(T) = T.isbitstype
 f31012(T) = Val(isbitstype(T))
-@test @inferred overdub(Ctx(), f31012, Int64) == Val(true)
+@test @inferred(overdub(Ctx(), f31012, Int64)) == Val(true)
+
+@generated bar(::Val{align}) where {align} = :(42)
+foo(i) = i+bar(Val(1))
 
+@test @inferred(overdub(Ctx(), foo, 1)) == 43
+
+# Check that misbehaving pure functions propagate their error
+Base.@pure func1() = 42
+Base.@pure func2() = (this_is_an_exception; func1())
+
+let method = which(func2, ())
+    mi = Core.Compiler.specialize_method(method, Tuple{typeof(func2)}, Core.svec())
+    mi.inInference = true
+end
+func3() = func2()
+@test_throws UndefVarError func3()