SI-5739 store sub-patterns in local vals

Also closes SI-5158 (debuggability), SI-6070 (soundness).

To improve both debuggability and soundness,
we now store the result of an extractor (user-defined and synthetic)
in local variables.

For the case class case, this also fixes the soundness bug SI-6070,
as this prevents post-match mutation of bound variables.

The core of the refactoring consisted of introducing the PreserveSubPatBinders
trait, which introduces local variables instead of substituting symbols
for the RHS of those variables (so this can be seen as reverting the premature optimization
of inline the case-class getters into the case body).

Since TreeMakerToCond fuses the substitutions performed in a match to find out
which symbolic values binders evaluate to, masquerade PreserveSubPatBinders's
binding of subPatBinders and subPatRefs as the corresponding substitution.

Consider `case class Foo(bar: Int)`, then `case y@Foo(x) => println(x)`
gives rise to `{val x = y.bar; println(x)}` (instead of `println(y.bar)`),
and `subPatternsAsSubstitution` pretends we still replace `x` by `y.bar`,
instead of storing it in a local variable so that the rest of the analysis need not be modified.

Misc notes:
- correct type for seq-subpattern
- more error resilience (ill-typed patterns sometimes slip past the typechecker -- reopened SI-4425)

TODO: come up with a more abstract framework for expressing bound symbols and their values

1 files changed, 40 insertions, 40 deletions

diff --git a/test/files/run/inline-ex-handlers.check b/test/files/run/inline-ex-handlers.check
index 7d96c447b0..25e1b2a4dd 100644
--- a/test/files/run/inline-ex-handlers.check
+++ b/test/files/run/inline-ex-handlers.check
@@ -34,11 +34,11 @@
 <     101	JUMP 4
 <     
 <   4: 
-512c517
+515c520
 <   blocks: [1,2,3,4,6,7,8,9,10]
 ---
 >   blocks: [1,2,3,4,6,7,8,9,10,11,12,13]
-541c546,551
+544c549,554
 <     306	THROW(MyException)
 ---
 >     ?	JUMP 11
@@ -47,7 +47,7 @@
 >     ?	LOAD_LOCAL(variable monitor4)
 >     305	MONITOR_EXIT
 >     ?	JUMP 12
-547c557,563
+550c560,566
 <     ?	THROW(Throwable)
 ---
 >     ?	JUMP 12
@@ -57,7 +57,7 @@
 >     304	MONITOR_EXIT
 >     ?	STORE_LOCAL(value t)
 >     ?	JUMP 13
-553c569,582
+556c572,585
 <     ?	THROW(Throwable)
 ---
 >     ?	STORE_LOCAL(value t)
@@ -74,19 +74,19 @@
 >     310	CALL_PRIMITIVE(EndConcat)
 >     310	CALL_METHOD scala.Predef.println (dynamic)
 >     310	JUMP 2
-577c606
+580c609
 <     catch (Throwable) in ArrayBuffer(7, 8, 9, 10) starting at: 6
 ---
 >     catch (Throwable) in ArrayBuffer(7, 8, 9, 10, 11) starting at: 6
-580c609
+583c612
 <     catch (Throwable) in ArrayBuffer(4, 6, 7, 8, 9, 10) starting at: 3
 ---
 >     catch (Throwable) in ArrayBuffer(4, 6, 7, 8, 9, 10, 11, 12) starting at: 3
-612c641
+615c644
 <   blocks: [1,2,3,4,5,6,7,9,10]
 ---
 >   blocks: [1,2,3,4,5,6,7,9,10,11,12]
-636c665,671
+639c668,674
 <     78	THROW(IllegalArgumentException)
 ---
 >     ?	STORE_LOCAL(value e)
@@ -96,7 +96,7 @@
 >     81	LOAD_LOCAL(value e)
 >     ?	STORE_LOCAL(variable exc1)
 >     ?	JUMP 12
-665c700,714
+668c703,717
 <     81	THROW(Exception)
 ---
 >     ?	STORE_LOCAL(variable exc1)
@@ -114,15 +114,15 @@
 >     84	STORE_LOCAL(variable result)
 >     84	LOAD_LOCAL(variable exc1)
 >     84	THROW(Throwable)
-687c736
+690c739
 <     catch (<none>) in ArrayBuffer(4, 6, 7, 9) starting at: 3
 ---
 >     catch (<none>) in ArrayBuffer(4, 6, 7, 9, 11) starting at: 3
-713c762
+716c765
 <   blocks: [1,2,3,4,5,6,9,12,14,17,18,19,22,25,27,28,30,31]
 ---
 >   blocks: [1,2,3,4,5,6,9,12,14,17,18,19,22,25,27,28,30,31,32,33,34]
-737c786,793
+740c789,796
 <     172	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
@@ -133,12 +133,12 @@
 >     170	STORE_LOCAL(value x4)
 >     170	SCOPE_ENTER value x4
 >     170	JUMP 18
-793c849,850
+798c854,855
 <     177	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
 >     ?	JUMP 33
-797c854,861
+802c859,866
 <     170	THROW(Throwable)
 ---
 >     ?	STORE_LOCAL(value ex6)
@@ -149,17 +149,17 @@
 >     169	STORE_LOCAL(value x4)
 >     169	SCOPE_ENTER value x4
 >     169	JUMP 5
-830c894,895
+837c901,902
 <     182	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(variable exc2)
 >     ?	JUMP 34
-834c899,900
+841c906,907
 <     169	THROW(Throwable)
 ---
 >     ?	STORE_LOCAL(variable exc2)
 >     ?	JUMP 34
-835a902,914
+842a909,921
 >   34: 
 >     184	LOAD_MODULE object Predef
 >     184	CONSTANT("finally")
@@ -173,19 +173,19 @@
 >     185	LOAD_LOCAL(variable exc2)
 >     185	THROW(Throwable)
 >     
-856c935
+863c942
 <     catch (Throwable) in ArrayBuffer(17, 18, 19, 22, 25, 27, 28, 30) starting at: 4
 ---
 >     catch (Throwable) in ArrayBuffer(17, 18, 19, 22, 25, 27, 28, 30, 32) starting at: 4
-859c938
+866c945
 <     catch (<none>) in ArrayBuffer(4, 5, 6, 9, 12, 17, 18, 19, 22, 25, 27, 28, 30) starting at: 3
 ---
 >     catch (<none>) in ArrayBuffer(4, 5, 6, 9, 12, 17, 18, 19, 22, 25, 27, 28, 30, 32, 33) starting at: 3
-885c964
+892c971
 <   blocks: [1,2,3,6,7,8,11,14,16,17,19]
 ---
 >   blocks: [1,2,3,6,7,8,11,14,16,17,19,20]
-909c988,995
+916c995,1002
 <     124	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
@@ -196,15 +196,15 @@
 >     122	STORE_LOCAL(value x4)
 >     122	SCOPE_ENTER value x4
 >     122	JUMP 7
-969c1055
+979c1065
 <     catch (IllegalArgumentException) in ArrayBuffer(6, 7, 8, 11, 14, 16, 17, 19) starting at: 3
 ---
 >     catch (IllegalArgumentException) in ArrayBuffer(6, 7, 8, 11, 14, 16, 17, 19, 20) starting at: 3
-995c1081
+1005c1091
 <   blocks: [1,2,3,4,5,8,11,15,16,17,19]
 ---
 >   blocks: [1,2,3,5,8,11,15,16,17,19,20]
-1019c1105,1114
+1029c1115,1124
 <     148	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
@@ -217,15 +217,15 @@
 >     154	LOAD_LOCAL(value x4)
 >     154	IS_INSTANCE REF(class MyException)
 >     154	CZJUMP (BOOL)NE ? 5 : 11
-1040,1042d1134
+1050,1052d1144
 <     145	JUMP 4
 <     
 <   4: 
-1275c1367
+1288c1380
 <   blocks: [1,2,3,4,5,7]
 ---
 >   blocks: [1,2,3,4,5,7,8]
-1299c1391,1398
+1312c1404,1411
 <     38	THROW(IllegalArgumentException)
 ---
 >     ?	STORE_LOCAL(value e)
@@ -236,16 +236,16 @@
 >     42	CONSTANT("IllegalArgumentException")
 >     42	CALL_METHOD scala.Predef.println (dynamic)
 >     42	JUMP 2
-1348c1447
+1361c1460
 <   blocks: [1,2,3,4,5,8,11,13,14,16,17,19]
 ---
 >   blocks: [1,2,3,5,8,11,13,14,16,17,19,20]
-1372c1471,1472
+1385c1484,1485
 <     203	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
 >     ?	JUMP 20
-1392c1492,1501
+1405c1505,1514
 <     209	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value ex6)
@@ -258,15 +258,15 @@
 >     212	LOAD_LOCAL(value x4)
 >     212	IS_INSTANCE REF(class MyException)
 >     212	CZJUMP (BOOL)NE ? 5 : 11
-1405,1407d1513
+1418,1420d1526
 <     200	JUMP 4
 <     
 <   4: 
-1467c1573
+1483c1589
 <   blocks: [1,2,3,4,5,7]
 ---
 >   blocks: [1,2,3,4,5,7,8]
-1491c1597,1604
+1507c1613,1620
 <     58	THROW(IllegalArgumentException)
 ---
 >     ?	STORE_LOCAL(value e)
@@ -277,11 +277,11 @@
 >     62	CONSTANT("RuntimeException")
 >     62	CALL_METHOD scala.Predef.println (dynamic)
 >     62	JUMP 2
-1540c1653
+1556c1669
 <   blocks: [1,2,3,4]
 ---
 >   blocks: [1,2,3,4,5]
-1560c1673,1678
+1576c1689,1694
 <     229	THROW(MyException)
 ---
 >     ?	JUMP 5
@@ -290,19 +290,19 @@
 >     ?	LOAD_LOCAL(variable monitor1)
 >     228	MONITOR_EXIT
 >     228	THROW(Throwable)
-1566c1684
+1582c1700
 <     ?	THROW(Throwable)
 ---
 >     228	THROW(Throwable)
-1594c1712
+1610c1728
 <   locals: value args, variable result, variable monitor2, variable monitorResult1
 ---
 >   locals: value exception$1, value args, variable result, variable monitor2, variable monitorResult1
-1596c1714
+1612c1730
 <   blocks: [1,2,3,4]
 ---
 >   blocks: [1,2,3,4,5]
-1619c1737,1745
+1635c1753,1761
 <     245	THROW(MyException)
 ---
 >     ?	STORE_LOCAL(value exception$1)
@@ -314,7 +314,7 @@
 >     ?	LOAD_LOCAL(variable monitor2)
 >     244	MONITOR_EXIT
 >     244	THROW(Throwable)
-1625c1751
+1641c1767
 <     ?	THROW(Throwable)
 ---
 >     244	THROW(Throwable)