fix #1013

compiler/sigmatch.nim

@@ -12,7 +12,7 @@
 
 import 
   intsets, ast, astalgo, semdata, types, msgs, renderer, lookups, semtypinst,
-  magicsys, condsyms, idents, lexer, options, parampatterns, strutils
+  magicsys, condsyms, idents, lexer, options, parampatterns, strutils, trees
 
 when not defined(noDocgen):
   import docgen
@@ -973,11 +973,17 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
     # fix the expression, so it contains the already instantiated types
     let instantiated = replaceTypesInBody(c.c, c.bindings, f.n)
     let reevaluted = c.c.semExpr(c.c, instantiated)
-    if reevaluted.typ.kind != tyTypeDesc:
+    case reevaluted.typ.kind
+    of tyTypeDesc:
+      result = typeRel(c, a, reevaluted.typ.base)
+    of tyStatic:
+      result = typeRel(c, a, reevaluted.typ.base)
+      if result != isNone and reevaluted.typ.n != nil:
+        if not exprStructuralEquivalent(aOrig.n, reevaluted.typ.n):
+          result = isNone
+    else:
       localError(f.n.info, errTypeExpected)
       result = isNone
-    else:
-      result = typeRel(c, a, reevaluted.typ.base)
   
   else:
     internalAssert false

tests/matrix/issue1013.nim

@@ -0,0 +1,23 @@
+import typetraits
+
+template reject(e: expr) =
+  static: assert(not compiles(e))
+
+type
+  TMatrix[T; M, N: static[int]] = array[M*N, T]
+
+proc `*`[T; R, N, C](a: TMatrix[T, R, N], b: TMatrix[T, N, C]): TMatrix[T, R, C] =
+  discard
+
+var m1: TMatrix[int, 6, 4]
+var m2: TMatrix[int, 4, 3]
+var m3: TMatrix[int, 3, 3]
+
+var m4 = m1*m2
+static: assert m4.M == 6 and m4.N == 3
+
+reject m1 * m3 # not compatible
+
+var m5 = m2 * m3
+static: assert high(m5) == 11 # 4*3 - 1
+