diff --git a/flang/test/Semantics/call03.f90 b/flang/test/Semantics/call03.f90
--- a/flang/test/Semantics/call03.f90
+++ b/flang/test/Semantics/call03.f90
@@ -153,7 +153,7 @@
     character :: ch1
     !ERROR: Actual argument variable length '1' is less than expected length '2'
     call ch2(ch1)
-    !WARN: Actual argument expression length '0' is less than expected length '2'
+    !WARNING: Actual argument expression length '0' is less than expected length '2'
     call ch2("")
     call pdtdefault(vardefault)
     call pdtdefault(var3)
diff --git a/flang/test/Semantics/case01.f90 b/flang/test/Semantics/case01.f90
--- a/flang/test/Semantics/case01.f90
+++ b/flang/test/Semantics/case01.f90
@@ -129,7 +129,8 @@
   end select
 
   select case (grade2)
-     case (51:50) ! warning
+     !WARNING: CASE has lower bound greater than upper bound
+     case (51:50)
      case (100:)
      case (:30)
      case (40)
@@ -182,13 +183,13 @@
   integer :: j
   select case(1_1)
   case (127)
-  !WARN: CASE value (128_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARNING: CASE value (128_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (128)
-  !WARN: CASE value (129_4) overflows type (INTEGER(1)) of SELECT CASE expression
-  !WARN: CASE value (130_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARNING: CASE value (129_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARNING: CASE value (130_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (129:130)
-  !WARN: CASE value (-130_4) overflows type (INTEGER(1)) of SELECT CASE expression
-  !WARN: CASE value (-129_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARNING: CASE value (-130_4) overflows type (INTEGER(1)) of SELECT CASE expression
+  !WARNING: CASE value (-129_4) overflows type (INTEGER(1)) of SELECT CASE expression
   case (-130:-129)
   case (-128)
   !ERROR: Must be a scalar value, but is a rank-1 array
diff --git a/flang/test/Semantics/common-blocks.f90 b/flang/test/Semantics/common-blocks.f90
--- a/flang/test/Semantics/common-blocks.f90
+++ b/flang/test/Semantics/common-blocks.f90
@@ -7,7 +7,7 @@
   common x, y
   common /a/ xa, ya
   common /b/ xb, yb
-  !CHECK: portability: Blank COMMON object 'x' in a DATA statement is not standard
+  !WARNING: Blank COMMON object 'x' in a DATA statement is not standard
   data x /42./, xa /42./, yb/42./
 end subroutine
 
@@ -19,5 +19,6 @@
   common /b/ xb, yb
   equivalence (yb, yb_eq)
   !ERROR: Multiple initialization of COMMON block /b/
+  !WARNING: Blank COMMON object 'x' in a DATA statement is not standard
   data x /66./, xa /66./, yb_eq /66./
 end subroutine
diff --git a/flang/test/Semantics/data06.f90 b/flang/test/Semantics/data06.f90
--- a/flang/test/Semantics/data06.f90
+++ b/flang/test/Semantics/data06.f90
@@ -42,6 +42,7 @@
   procedure(rfunc), pointer :: rpp
   real, target :: rt
   !ERROR: Data object 'rt' may not be used to initialize 'rpp', which is a procedure pointer
+  !WARNING: Procedure pointer 'rpp' in a DATA statement is not standard
   data rpp/rt/
   !ERROR: Initializer for 'rt' must not be a pointer
   data rt/null()/
diff --git a/flang/test/Semantics/dosemantics02.f90 b/flang/test/Semantics/dosemantics02.f90
--- a/flang/test/Semantics/dosemantics02.f90
+++ b/flang/test/Semantics/dosemantics02.f90
@@ -23,10 +23,12 @@
   INTEGER, PARAMETER :: constInt = 0
 
   ! Warn on this one for backwards compatibility
+  !WARNING: DO step expression should not be zero
   DO 10 I = 1, 10, 0
   10 CONTINUE
 
   ! Warn on this one for backwards compatibility
+  !WARNING: DO step expression should not be zero
   DO 20 I = 1, 10, 5 - 5
   20 CONTINUE
 
diff --git a/flang/test/Semantics/dosemantics12.f90 b/flang/test/Semantics/dosemantics12.f90
--- a/flang/test/Semantics/dosemantics12.f90
+++ b/flang/test/Semantics/dosemantics12.f90
@@ -392,6 +392,7 @@
 
   call intentInOutSub(jvar, ivar)
   do ivar = 1,10
+    !WARNING: Possible redefinition of DO variable 'ivar'
     call intentInOutSub(jvar, ivar)
   end do
 
@@ -435,8 +436,8 @@
     jvar = 83 + intentInFunc(intentOutFunc(ivar))
   end do
 
-  ! Warning for passing a DO variable to an INTENT(INOUT) dummy
   do ivar = 1, 10
+    !WARNING: Possible redefinition of DO variable 'ivar'
     jvar = intentInOutFunc(ivar)
   end do
 
diff --git a/flang/test/Semantics/forall01.f90 b/flang/test/Semantics/forall01.f90
--- a/flang/test/Semantics/forall01.f90
+++ b/flang/test/Semantics/forall01.f90
@@ -42,6 +42,7 @@
   forall(i=1:10)
     forall(j=1:10)
       !ERROR: Cannot redefine FORALL variable 'i'
+      !WARNING: FORALL index variable 'j' not used on left-hand side of assignment
       i = 1
     end forall
   end forall
@@ -81,14 +82,18 @@
     x(i) = y(i)
   end forall
   forall(i=1:10)
-    x = y  ! warning: i not used on LHS
+    !WARNING: FORALL index variable 'i' not used on left-hand side of assignment
+    x = y
     forall(j=1:10)
-      x(i) = y(i)  ! warning: j not used on LHS
-      x(j) = y(j)  ! warning: i not used on LHS
+      !WARNING: FORALL index variable 'j' not used on left-hand side of assignment
+      x(i) = y(i)
+      !WARNING: FORALL index variable 'i' not used on left-hand side of assignment
+      x(j) = y(j)
     endforall
   endforall
   do concurrent(i=1:10)
     x = y
+    !WARNING: FORALL index variable 'i' not used on left-hand side of assignment
     forall(i=1:10) x = y
   end do
 end
@@ -101,6 +106,7 @@
   real, target :: b(10)
   forall(i=1:10)
     a(i)%p => b(i)
-    a(1)%p => b(i)  ! warning: i not used on LHS
+    !WARNING: FORALL index variable 'i' not used on left-hand side of assignment
+    a(1)%p => b(i)
   end forall
 end
diff --git a/flang/test/Semantics/int-literals.f90 b/flang/test/Semantics/int-literals.f90
--- a/flang/test/Semantics/int-literals.f90
+++ b/flang/test/Semantics/int-literals.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 ! Fortran syntax considers signed int literals in complex literals
 ! to be a distinct production, not an application of unary +/- to
 ! an unsigned int literal, so they're used here to test overflow
diff --git a/flang/test/Semantics/resolve11.f90 b/flang/test/Semantics/resolve11.f90
--- a/flang/test/Semantics/resolve11.f90
+++ b/flang/test/Semantics/resolve11.f90
@@ -4,7 +4,7 @@
   integer, private :: j
   !ERROR: The accessibility of 'i' has already been specified as PUBLIC
   private i
-  !The accessibility of 'j' has already been specified as PRIVATE
+  !WARNING: The accessibility of 'j' has already been specified as PRIVATE
   private j
 end
 
diff --git a/flang/test/Semantics/resolve31.f90 b/flang/test/Semantics/resolve31.f90
--- a/flang/test/Semantics/resolve31.f90
+++ b/flang/test/Semantics/resolve31.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 ! C735 If EXTENDS appears, SEQUENCE shall not appear.
 ! C738 The same private-or-sequence shall not appear more than once in a
 ! given derived-type-def .
@@ -49,8 +49,10 @@
   type :: t1
     private
     sequence
-    private  ! not a fatal error
-    sequence ! not a fatal error
+    !WARNING: PRIVATE may not appear more than once in derived type components
+    private
+    !WARNING: SEQUENCE may not appear more than once in derived type components
+    sequence
     real :: t1Field
   end type
   type :: t1a
@@ -83,7 +85,7 @@
     class(*), allocatable :: typeStarField
     !ERROR: A sequence type data component must either be of an intrinsic type or a derived sequence type
     type(plainType) :: testField1
-    !Pointers are ok as an extension
+    !WARNING: A sequence type data component that is a pointer to a non-sequence type is not standard
     type(plainType), pointer :: testField1p
     type(sequenceType) :: testField2
     procedure(real), pointer, nopass :: procField
diff --git a/flang/test/Semantics/resolve59.f90 b/flang/test/Semantics/resolve59.f90
--- a/flang/test/Semantics/resolve59.f90
+++ b/flang/test/Semantics/resolve59.f90
@@ -59,9 +59,11 @@
     x = acos(f5)
   end function
   ! Sanity test: f18 handles C1560 violation by ignoring RESULT
-  function f6() result(f6) !OKI (warning)
+  !WARNING: The function name should not appear in RESULT, references to 'f6' inside the function will be considered as references to the result only
+  function f6() result(f6)
   end function
-  function f7() result(f7) !OKI (warning)
+  !WARNING: The function name should not appear in RESULT, references to 'f7' inside the function will be considered as references to the result only
+  function f7() result(f7)
     real :: x, f7
     !ERROR: Recursive call to 'f7' requires a distinct RESULT in its declaration
     x = acos(f7())
diff --git a/flang/test/Semantics/test_errors.py b/flang/test/Semantics/test_errors.py
--- a/flang/test/Semantics/test_errors.py
+++ b/flang/test/Semantics/test_errors.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
-"""Compiles a source file and checks errors against those listed in the file.
+"""Compiles a source file and checks errors and warnings against those
+   listed in the file.
 
 Parameters:
     sys.argv[1]: a source file with contains the input and expected output
@@ -19,8 +20,10 @@
 srcdir = cm.set_source(sys.argv[1])
 with open(srcdir, 'r') as f:
     src = f.readlines()
-actual = ""
-expect = ""
+err_actual = ""
+err_expect = ""
+warn_actual = ""
+warn_expect = ""
 diffs = ""
 log = ""
 
@@ -34,6 +37,7 @@
     try:
         proc = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               check=True, universal_newlines=True, cwd=tmpdir)
+        log = proc.stderr
     except subprocess.CalledProcessError as e:
         log = e.stderr
         if e.returncode >= 128:
@@ -44,25 +48,42 @@
 for line in log.split('\n'):
     m = re.search(r"[^:]*:(\d+:).*(?:error:)(.*)", line)
     if m:
-        actual += m.expand(r"\1\2\n")
+        err_actual += m.expand(r"\1\2\n")
+for line in log.split('\n'):
+    m = re.search(r"[^:]*:(\d+:).*(?:warning:|portability:)(.*)", line)
+    if m:
+        warn_actual += m.expand(r"\1\2\n")
 
-# Gets the expected errors and their line number
+# Gets the expected diagnostics and their line number
 errors = []
+warnings = []
 for i, line in enumerate(src, 1):
-    m = re.search(r"(?:^\s*!\s*ERROR: )(.*)", line)
-    if m:
-        errors.append(m.group(1))
+    me = re.search(r"(?:^\s*!\s*ERROR: )(.*)", line)
+    mw = re.search(r"(?:^\s*!\s*WARNING: )(.*)", line)
+    if me:
+        errors.append(me.group(1))
+        continue
+    if mw:
+        warnings.append(mw.group(1))
         continue
     if errors:
         for x in errors:
-            expect += f"{i}: {x}\n"
+            err_expect += f"{i}: {x}\n"
         errors = []
+    if warnings:
+        for x in warnings:
+            warn_expect += f"{i}: {x}\n"
+        warnings = []
 
-# Compares the expected errors with the compiler errors
-for line in unified_diff(actual.split("\n"), expect.split("\n"), n=0):
+# Compares the expected errors and warnings with the compiler diagnostics
+for line in unified_diff(err_actual.split("\n"), err_expect.split("\n"), n=0):
     line = re.sub(r"(^\-)(\d+:)", r"\nactual at \g<2>", line)
     line = re.sub(r"(^\+)(\d+:)", r"\nexpect at \g<2>", line)
     diffs += line
+for line in unified_diff(warn_actual.split("\n"), warn_expect.split("\n"), n=0):
+    line = re.sub(r"(^\-)(\d+:)", r"\nactual warning at \g<2>", line)
+    line = re.sub(r"(^\+)(\d+:)", r"\nexpected warning at \g<2>", line)
+    diffs += line
 
 if diffs != "":
     print(diffs)