don't sign-extend signed unsized numbers with a leading 1 bit

I'm opting for iverilog's interpretation of the specifications here. The
commercial simulators I tested seem to agree.

.github/workflows/main.yaml

@@ -41,7 +41,7 @@ jobs:
           - macOS-11
     needs: build
     env:
-      IVERILOG_REF: 8ee1d56e1acbc130aa63da3c8ef0d535a551cf28
+      IVERILOG_REF: f31d0dcbc5ddcd97e1e2e6f7bc7eb0f5a547fe16
     steps:
       - uses: actions/checkout@v1
       - name: Install Dependencies (macOS)

CHANGELOG.md

@@ -17,6 +17,8 @@
 ### Bug Fixes
 
 * Fixed an issue that prevented parsing tasks and functions with `inout` ports
+* Fixed signed unsized literals with a leading 1 bit (e.g., `'sb1`, `'sh8f`)
+  incorrectly sign-extending in size and type casts
 * Fixed conflicting genvar names when inlining interfaces and modules that use
   them; all genvars are now given a design-wide unique name
 * Fixed byte order of strings in size casts

src/Language/SystemVerilog/AST/Number.hs

@@ -153,12 +153,17 @@ parseNormalized oversizedNumbers str =
 
         -- high-order X or Z is extended up to the size of the literal
         leadDigit = head digits
-        numDigits = length digits
+        numDigits = length digits + if isSignedUnsizedWithLeading1 then 1 else 0
         leadDigitIsXZ = elem leadDigit xzDigits
         digitsExtended =
             if leadDigitIsXZ
                 then replicate (sizeDigits - numDigits) leadDigit ++ digits
                 else digits
+        isSignedUnsizedWithLeading1 =
+            maybeBase /= Nothing &&
+            not leadDigitIsXZ &&
+            signed &&
+            digitToInt leadDigit >= div (baseSize base) 2
 
         -- determine the number of digits needed based on the size
         sizeDigits = ((abs size) `div` bitsPerDigit) + sizeExtraDigit

test/core/cast_literal.vh

@@ -47,6 +47,16 @@
 `TEST_ALL(7'so0x)
 `TEST_ALL(7'sox1)
 `TEST_ALL(7'soz0)
+`TEST_ALL('so7)
+`TEST_ALL('so37)
+`TEST_ALL('so47)
+`TEST_ALL('so57)
+`TEST_ALL('so07)
+`TEST_ALL('o7)
+`TEST_ALL('o37)
+`TEST_ALL('o47)
+`TEST_ALL('o57)
+`TEST_ALL('o07)
 
 `TEST_ALL('bx)
 `TEST_ALL('ozx)
@@ -58,6 +68,18 @@
 `TEST_ALL('bzzz1)
 `TEST_ALL('ozzz1)
 `TEST_ALL('hzzz1)
+`TEST_ALL('shf)
+`TEST_ALL('sh6f)
+`TEST_ALL('sh7f)
+`TEST_ALL('sh8f)
+`TEST_ALL('sh9f)
+`TEST_ALL('sh0f)
+`TEST_ALL('hf)
+`TEST_ALL('h6f)
+`TEST_ALL('h7f)
+`TEST_ALL('h8f)
+`TEST_ALL('h9f)
+`TEST_ALL('h0f)
 
 `TEST_ALL(1'ox)
 `TEST_ALL(1'oz)