ci: fix strict-warnings on gcc-13/clang-18 and cross regression build

The strict lane surfaced more on the CI compilers than on older local
ones (verified against gcc 13 / clang 18):

* gcc: zero-init nadj in the float lgammaf_r too (same guarded
  false-positive as the double/long-double versions).
* clang 18 renamed the int->float conversion diagnostic to
  -Wimplicit-const-int-float-conversion; suppress that spelling as well.
* clang: suppress -Wdeprecated-non-prototype (C23) for the lane; the K&R
  definitions in w_cabs*.c and bsdsrc/b_*.c are left for a focused
  prototype-conversion follow-up.

Cross CI: build the regression programs with the cross toolchain in the
"Build tests" step and pass the toolchain vars to the qemu run, so the
foreign-arch regression binaries are produced by $TRIPLE-gcc instead of
the host compiler. Verified locally by cross-building for riscv64 and
running the regression test under qemu.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ViralBShah

.github/workflows/cross.yml

@@ -57,9 +57,12 @@ jobs:
       - name: Build with ${{ matrix.config.triple }}-gcc
         run: make -j$(nproc) ARCH=$ARCH TOOLPREFIX=$TRIPLE- ${CC:+CC=$CC} ${AR:+AR=$AR}
       - name: Build tests
-        run: make -j$(nproc) -C test ARCH=$ARCH TOOLPREFIX=$TRIPLE- ${CC:+CC=$CC} ${AR:+AR=$AR}
+        # Build the regression programs with the cross toolchain too, so the
+        # run step below only executes them (under qemu) rather than trying to
+        # rebuild them with the host compiler.
+        run: make -j$(nproc) -C test all regression-build ARCH=$ARCH TOOLPREFIX=$TRIPLE- ${CC:+CC=$CC} ${AR:+AR=$AR}
       - name: Run tests under qemu
         env:
           QEMU_LD_PREFIX: /usr/${{ matrix.config.triple }}
           LD_LIBRARY_PATH: .
-        run: make test
+        run: make test ARCH=$ARCH TOOLPREFIX=$TRIPLE- ${CC:+CC=$CC} ${AR:+AR=$AR}

Make.inc

@@ -165,14 +165,21 @@ CFLAGS_add += -std=c99 -Wall -I$(OPENLIBM_HOME) -I$(OPENLIBM_HOME)/include -I$(O
 WERROR ?= 0
 ifeq ($(WERROR),1)
 CFLAGS_add += -Werror
-# Two clang-only diagnostics are silenced for the strict lane (gcc ignores
+# A few clang-only diagnostics are silenced for the strict lane (gcc ignores
 # unknown -Wno-* options, so this is safe for both compilers):
-#  * -Wimplicit-int-float-conversion: s_lround/s_llround deliberately round
-#    DTYPE_MAX through (dtype)x; the boundary arithmetic is correct by design.
+#  * -Wimplicit-int-float-conversion / -Wimplicit-const-int-float-conversion:
+#    s_lround/s_llround deliberately round DTYPE_MAX through (dtype)x; the
+#    boundary arithmetic is correct by design. (clang renamed the const form
+#    around clang 18, so both spellings are listed.)
 #  * -Wignored-attributes: the extern-inline fenv re-declarations in
-#    openlibm_fenv_*.h trip a harmless attribute-placement diagnostic; tracked
-#    separately rather than reworked under the warnings sweep.
-CFLAGS_add += -Wno-implicit-int-float-conversion -Wno-ignored-attributes
+#    openlibm_fenv_*.h trip a harmless attribute-placement diagnostic.
+#  * -Wdeprecated-non-prototype: a handful of old K&R-style definitions
+#    (w_cabs*.c, bsdsrc/b_*.c) that C23 deprecates; converting them to ANSI
+#    prototypes is left to a focused follow-up rather than this CI change.
+CFLAGS_add += -Wno-implicit-int-float-conversion \
+              -Wno-implicit-const-int-float-conversion \
+              -Wno-ignored-attributes \
+              -Wno-deprecated-non-prototype
 endif
 ifneq ($(filter $(ARCH),i387 amd64 powerpc),)
 CFLAGS_add += -I$(OPENLIBM_HOME)/ld80

src/e_lgammaf_r.c

@@ -141,6 +141,7 @@ __ieee754_lgammaf_r(float x, int *signgamp)
 	float t,y,z,nadj,p,p1,p2,p3,q,r,w;
 	int32_t hx;
 	int i,ix;
+	nadj = 0;	/* only set & used when hx<0; init silences -Wmaybe-uninitialized */
 
 	GET_FLOAT_WORD(hx,x);